A Tentative Study of the English Tense from a Metaphorical Perspective

The English tense system has always been one of the main subjects for linguists and grammarians. This paper adopts the metaphorical approach to study the English tense. By analyzing the prototypical uses of the present tense and the past tense, the author gives a convincing and reasonable explanation of these various uses of the English tense. The metaphorical approach used in this paper provides a new perspective for the study of the English tense. The metaphorical mapping processes of the past tense and the present tense reflect the universal cognitive mechanism of human beings, that is, learners acquire knowledge from known to unknown. The last but not least, the new interpretations of the different uses of the English tense offers a practical help for the teaching and learning of tense.


Introduction
Tense in English originates from Italian (Tempo) and the Italian took it from the Latin word Tempos, whose literal meaning is time.The first person who confirmed the concept of tense is the philosopher Protagoras in the 5th century BC (Liu, 2002, p. 12).The ancient Greek grammarian Dionisius Thrax put forward a more detailed analysis of tense and he divided tense into three forms: present, past, future.The famous Latin grammarian Priscian carried out an analysis of Latin grammar on the basis of the grammatical system put forward by Thrax (Liu, 2002, p. 14).Later in 18 century, the famous English grammarian Harris claimed that the most obvious time distinction is past, present and future (Harris, 1968, p. 97).It is obvious that tense as time distinction in English grammar is profoundly influenced by ancient Latin grammatical framework.
With the development of linguistic research, the study of English grammar has become more and more comprehensive.There have been lots of arguments and debates as for the number of the English tense, which caused different definitions of tense.Poutsma (1926), Curme (1931), Alexander (1991) and Zhang (1995) are tense-advocators think that English has six tenses.There are four absolute tenses (present, past, present perfect and future), which express time from the standpoint of the moment at which the speaker is speaking without reference to any other act; and two relative tenses (past perfect and future perfect), which express time relative to the preceding absolute tenses.Quirk, et al. (1985, p. 175) state, "English has two tenses: PRESENT TENSE and PAST TENSE.As the names imply, the present tense normally refers to present time and past tense, past time."Zhang (1995, p. 406) claims, "Tense is a grammatical category of the verb, it is the verb form to express time distinctions.The English verb has two tenses with it, namely the PRESENT TENSE and the PAST TENSE".This paper will adopt the bi-tense view in order to make the relevant research and analysis easier.

Significance of the Study
The tense category is one of the subjects in which linguists and grammarians are interested.Most contemporary English grammarians have exerted many efforts to give a comprehensive description of the various uses of the English tense, but they fail to offer a coherent explanation for the fact that in English both the present tense and the past tense can be used to express events/states in the past, present and future, which makes the English tense difficult both to interpret and to learn.Chinese learners, whose foreign language is English, are often confused with the uses of the English tense because in Chinese language we do not have tense at all.There is no verb inflection in the Chinese language.What's more, the grammar books often teach rigid rules of tense use, which makes English tense study complicated.
Having realized the limitations of the previous studies, this paper will offer a unified and reasonable explanation of the various uses of the English tense, based on the conceptual metaphor theory under the guidance of cognitive linguistics.This study broadens the scope of metaphor research and provides a new perspective for the study of the English tense.Also, the new interpretation of the various uses of the English tense offers a practical help for the learning and teaching of the English tense in China.The paper reveals the cognitive process in which people extend the prototypical use of the past tense and the present tense to other domains.This notion of tense can be accepted more easily and is helpful for the acquisition of the English tense.

Literature Review
There are many grammarians and linguists who have studied the English tense at home and abroad, such as Quirk, et al., Curme, Comrie, Langacker, Taylor and Yi Zhongliang.The previous studies have laid a good foundation for further exploration.
3. 1 Quirk,et al.'s View According to Quirk, et al. (1972), English has two tenses: PRESENT TENSE and PAST TENSE.Quirk, et al. (1972) classify the simple present tense into four groups.The first one is the present tense without reference to speech time, which includes "eternal truths", which do not refer specifically to the present moment but are general timeless statements.We may distinguish two related types: universal time statement and habitual time statements (Quirk, et al., 1972, p. 100).Example (1) belongs to the universal statement, and example (2) belongs to the habitual statement.
(1) One and two make three.
(2) We get up early every morning.
The second group is the instantaneous simple present, which is used only with dynamic verbs that signify an event simultaneous with the present moment.The following sentence is a typical example: (3) Ellen passes the ball to Alison.
The third group is the present tense with future time reference, which can be used in two kinds of sentences: one is when there is a temporal adverbial in the clause, the other is conditional and temporal clauses introduced by if, unless, after, before, etc (Quirk, et al., 1972, p. 101).Take (4) and ( 5) as examples: (4) The train leaves for Beijing at six o'clock.
(5) Turn off the light before you leave.
The fourth group is the present tense with past time reference, which is used with the "communication verbs" such as tell, hear, learn, write, etc. to express the persistence in the present of the effect of a past communication.Examples (6) belong to this group: (6) I hear they have got another good harvest.Quirk, et al. (1985, p. 183-187) claim that there are two kinds of grammatical meaning in the past tense, that is, marking past time and marking present moment/future time.They also point out that the meaning of the past tense marking past time has two features: a. Event or thing is bound to happen in the past, and there is a gap between the ending time and present moment.
b.The speaker or the writer is sure to know the definite time when an event happens or a state exists.
Then, Quirk, et al. (1985) classify the grammatical meaning marking present moment and future time into three categories: a.The past tense in the reporting verb tends to make the verb of the subordinate clause use the past tense form; this phenomenon is called "back-shift".b.Attitudinal past is related to the attitudes of the speaker rather than to time.When verbs expressing volition or mental states are used in the past tenses, they reflect the euphemistic and tentative attitude of the speaker, rather than past time.c.Hypothetical past is used in some subordinate clauses, especially if clauses.(Quirk, et al., 1985) Quirk, et al. have done much research on the English tense.They adopt the "divide and rule" strategy, attempting to put the various uses of the present tense and the past tense into the general frame of time relationship.

Langacker's View
Langacker studies tense from the perspective of cognitive linguistics.He argues that tense locates the designated process with reference to the time of speech event (Langacker, 2004, p. 195).According to Langacker (2004), English has two tenses: present and past tense (future being marked by a modal).While their fundamental semantic characterization pertains to epistemic distance, they are prototypically construed with reference to the time-line model.Immediacy and non-immediacy are equal to present and past time.Therefore, Langacker (2004, p. 250) claims that the present tense indicates the occurrence of a full instantiation of the profiled process that precisely coincides with the time of speaking; the past tense indicates the occurrence of a full instantiation of the profiled process prior to the time of speaking.The perspective Langacker uses to explain the contrast between the form and meaning of tense is completely new.Langacker (2004) points out that the present tense and the past tense are grounding predications that relate a situation to an "epistemic" domain.In addition, he relates the proximal/distal contrast to the present/past distinction.In other words, the English present and past tense forms signal a proximal/distal distinction, whereby the present/past time interpretation is merely one possible instantiation of this distinction, albeit the prototypical one.The proximal form indicates that the situation described is actual and immediate to the ground (in particular the time of speaking).The distal form indicates the non-immediacy of the situation described: distance within reality normally amounts to the past tense (Langacker, 2004, p. 141).The term distal suggests distance from the ground not in a temporal but in an epistemic sense.
Langacker's theory of the English tense is mainly based on the notion of grounding, designating the process of establishing a conceptual relationship with the communicative scene.Langacker's view is quite different from the traditional analysis, especially the idea that the present tense stands for proximity and the past tense stands for distance, which gives us some clue in the image schema analysis.However, the grounding principle is a little abstract and hard to understand, especially for people who are seldom interested in linguistics.

Taylor's View
Taylor (2001) tries to study the past tense with the prototype theory, pioneered by Eleanor Rosh, who claims a category is defined in relation to a prototype and entities in this category can be divided into central and peripheral members.Taylor points out that polysemy is not a property of words alone, the tense category also exhibit a cluster of related meanings.Taylor (2001) explains, "The past tense is used, first and foremost, to locate an event or state at some point or period in time prior to the moment of speaking (or writing)."In Taylor's opinion, the past time use is the prototypical meaning of the past tense, by extension also including the historical narrative and fictional narrative.The second use of the past tense is to indicate the unreality (or counterfactuality) of an event or state, which is restricted to a small number of environments, including (a) if-conditionals, (b) expressions of wishes and desires and (c) suppositions and suggestions.Take the following sentences as examples: The third use is the use of the past tense as pragmatic softener, as instances of ( 10), (11), and ( 12).
(10) Could you pass me the book?(11) Ann might know?(12) You should speak to her.Taylor (2001) concludes that the past tense is a polysemic category.The past time use of the past tense (i.e. the temporal location prior to the speech moment) is more typical and salient, which is the central member or the prototype.The other two uses are the peripheral members.The use of pragmatic softening is even more peripheral.All the uses share the same family resemblance: remoteness.Taylor also tries to study the cognition processing of the softening function (i.e. the politeness form of the past tense), which seems to involve a double metaphorization.
Based on his analysis, we represent the metaphorical mapping in Figure 1.The first metaphor is the mapping from the space domain (source domain) to the time domain (target domain); the second metaphor applies the schema of distance and proximity to the domain of involvement.Distance is produced in the process of mapping because of the potential similarities between the source domain and the target domain.By using the past tense, the speaker distances himself from the speech act that he is performing.The past tense can function as a kind of pragmatic softener.
Although the specific process of the metaphorical mapping is not covered by Taylor, his study on the past tense gives us some enlightenment.This paper will follow his metaphorical approach to analyze the English tense.

The Conceptual Metaphor Theory
Metaphor has been an object of study since Aristotle and Mozi.In the west, there have been many different approaches to metaphor, including the Aristotelian approach, the traditional linguistics approach, the pragmatic approach of Searle and the interactionist approach.In 1980 Lakoff and Johnson co-authored Metaphors We Live By and opened a new era of metaphor study.Lakoff and Johnson (1980, p. 3-5) claim, "Metaphor is pervasive in everyday life, not just in language but in thought and action….Our ordinary conceptual system, in terms of which we both think and act, is fundamentally metaphorical in nature.The essence of metaphor is understanding and experiencing one kind of thing in terms of another".Lakoff (1993, p. 203) defines metaphor as a cross-domain mapping in the conceptual system.The conceptual metaphor theory, set up by Lakoff and Johnson, is one of the most influential theories now, which treats metaphor as a kind of mappings from familiar, concrete domains to less familiar and abstract ones.Its mental basis is not the similarities existing between domains, but abstract image schema.The basic premise of the conceptual metaphor theory is that metaphor is not simply a stylistic feature of language, and that thought its self is fundamentally metaphorical in nature.
Over 20 years, this approach has been developed by Lakoff (1980Lakoff ( , 1987Lakoff ( , 1990Lakoff ( , & 1993) ) and other scholars, such as Johnson (1980Johnson ( , 1987) ) and Turner (1990Turner ( , 1991)).The basic views of the theory can be listed in the following lines: a. Metaphor, as a phenomenon, is not just a matter of language, but of thought and reason.Metaphor involves both conceptual mapping and individual linguistic expressions.Lakoff and Johnson (1980) use mnemonics to suggest the mapping.Mnemonic names typically have the form: X IS Y, where X is the name of the target domain and Y is the name of the source domain.Since the mapping is primary while the language is secondary, we have reserved the term metaphor for the mapping rather than for the linguistic expressions.Lakoff (1993) states, mapping are a fixed pattern of ontological correspondences that map knowledge about the source domain to the target domain.
b. Metaphor is ubiquitous: Lakoff and Johnson (1980) provide evidence for the ubiquity of metaphor from the analysis of a large number of everyday utterances.They demonstrate that common expressions is like that the foundation for your theory and the argument collapsed are actually linguistic manifestation of a conceptual metaphor THEORIES ARE BUILDING.Expressions such as what he said left a bad taste in my mouth and Let me stew over that for a while reflect another conceptual metaphor IDEAS ARE FOOD.c. Metaphor is conceptual in nature: Metaphor is not a figure of speech, but a figure of thought, a conceptual or cognitive organization expressed by the linguistic object.Take the above conceptual metaphors as an example: we talk about theories and ideas in terms of building and food respectively because we conceive them through our concepts of building and food, and we act according to the way we conceive things.d.Metaphor is systematic: Different metaphorical concepts form a coherent network which underlines both our speech and thought.We can take the three conceptual metaphors of TIME for illustration: TIME IS MONEY (How do you spend your time these days?)all metaphorical concepts because they reflect the way we use our every day experiences with money, limited resources and valuable commodities to conceptualize time.And they form a coherent system since in our society money is a limited resource, which is in turn a valuable commodity.e. Metaphor is composed of two domains, a relatively more clearly structured source domain and a relatively less clearly structured target domain.It is mapping of the schematic structure of the source domain to that of the target domain.Its mental basis is not the similarities existing between domains, but abstract image schema.Metaphor mapping is not arbitrary, but grounded in our bodily experience.
Metaphor is a cross-domain mapping in the conceptual system, which can help us to understand abstract things in terms of concrete things.The prototypical uses of the past tense and the present tense both indicate temporal relations, which can be mapped onto other domains, such as the reality domain and the psychology domain.Thus, some "abnormal" uses of the present tense and past tense can get reasonable explanations with the help of the conceptual metaphor theory.

Image Schema
An image schema is a dynamic pattern that functions somewhat like the abstract structure of an image and it is manifested in rich images, perceptions and events (Johnson, 1987, p. 2).The notion of image schema is closely associated with the development of the embodied cognition thesis, offered by early researchers in cognitive semantics, such as Lakoff and Johnson.In his book The Body in the Mind, Johnson (1987) indicates that embodied experience gives rise to image schema within the conceptual system.Image schema are not considered to be innate knowledge structures; they derive from sensory and perceptual experience as we interact with and move about in the world.
The term image in image schema is equivalent to the use of this term in psychology, where imagistic experience relates to and derives from our experience of the external world.Another term of this type of experience is sensory experience, because it comes from sensory-perceptual mechanisms.Image schema is often discussed together with metaphor, as these two terms are interrelated.Lakoff (1990) points out that metaphor is based on image schema.
There are countless experiences in our daily life, which have a starting point and an ending point.The following sentences can best illustrate this point: (13) We go to school from home.
(14) Look at the queue from the gate to the street.
(15) A water drop fell from the eave onto the ground.
(16) The highway links Beijing and Tianjin.
All these follow a spatial path from one point to another.From these the path image schema can be abstracted, which has a starting point A and an ending point B. (See Figure 2) Figure 2. The path image schema (Evans & Green, 2006, p. 185) Examples ( 13)-( 16) are taken from the physical and spatial world, that is, from the physical or concrete domains.Once this image schema of path is extracted, it can be extended to other abstract domains through metaphorical mapping.For instance, Birth is the beginning of life; death is the end and Life has a beginning as well as an end.Therefore, birth and death are abstracted as two points, which constitutes the path image schema.The sentences make use of the path image schema and project it from the original concrete domain to domains that are more abstract.From the above discussion, we can get a clear understanding about the notion of image schema.
The importance of image schema is that they can provide the concrete basis for metaphorical mapping, and these metaphorical mapping can give a unified interpretation of the various uses of the English tense.Lakoff (1993, p. 206-207) states, "…the metaphor can be understood as a mapping (in the mathematical sense) from a source domain to a target domain.The mapping is tightly structured…Metaphors are mapping, that is, sets of conceptual correspondences".

Cross-domain Mapping
Each metaphor consists of a source domain and a target domain.A domain in the conceptual metaphor theory is a body of knowledge that organizes related concepts (Evans & Green, 2006, p. 190).Target domains tend to be more abstract, lacking physical characteristics and therefore more different to understand and talk about in their own terms.In contrast, source domains tend to be more concrete and therefore more readily graspable.The source domain is the comparison concept while the target domain is the described concept.Koveeses (2002) holds that the most common source domains are human body, animals, plants, food and forces.The most common target domains are morality, time, emotions, and thoughts.
Since this paper is the study of the English tense, so let us introduce the TIME-AS-SPACE mapping.It is generally agreed that the notions of time are expressed in terms of space in various languages.Lakoff (1993) states that in English the general conceptual metaphor of time is TIME PASSING IS MOTION.Specifically, time is understood in terms of things (i.e.entities & locations) and motion.Furthermore, when we take a philosophical point of view, space and time are the basic existence form of substance.Everything exists in space and time.Objects move within space and time.Lakoff and Johnson (1980) point out that the majority of basic concepts are constructed through one or more spatial metaphorical mapping.For example, there are conceptual metaphors like HAPPY IS UP, SAD IS DOWN; GOOD IS UP, BAD IS DOWN; RATIONAL IS UP, EMOTIONAL IS DOWN under the orientational concepts pair UP-DOWN.The space domain serves as an important basis for human activities.Through researches of cognitive linguists, it can be hypothesized that the TIME IS SPACE metaphor is universal, reflecting the general process of human cognition in which time has to be understood, and reasoned about in spatial terms.

A Tentative Study of the Past Tense from a Metaphorical Perspective
The conceptual metaphor theory and the notions of image schema and cross-domain mapping been discussed above is the theoretical basis of the study of the English tense.As we have claimed this paper adopts the bi-tense view that there are only two tenses in English including the present tense and the past tense.Thus, the past tense and the present tense will be discussed in the following part in terms of metaphor.

The Prototypical Use of the Past Tense
The past tense, which is originally used to denote temporal relation, is called the preterit in Latin, whose literal meaning is "gone by".Let us start with some sentences: (17) He lived in Beijing for ten years.
(19) We visited Paris last week.Leech (1978, p. 9) says that the above sentences are normal use in reference to past time, and there are two elements of meaning involved in the commonest use of the past tense.One is "the happenings took place before the present moment" and the other is "the speaker has a definite time in mind".Quirk et al. (1972) argues that the basic meaning of the past tense is to denote past time.There is a gap between the ending time and present moment.According to Comrie, (see Figure 3), time can be represented as a straight line, with the past represented conventionally to the left and the future to the right.The present moment is represented by a point labeled "O" on the line.This representation enables us to represent diagrammatically a range of ordinary-language statements about time.For instance, to say that an event occurred in the past is to locate it diagrammatically to the left of O.The meaning of the past tense is thus location in time prior to the present moment (Comrie, 2005, p. 41).
The verbs in sentences ( 17)-( 19) simply express happenings that took place in the past before the present moment including the moment of speaking and writing.This paper holds that the prototypical use of the past tense refers to past time, or the past event/state.We have claimed above that the notions of time are expressed in terms of space.Time can be understood and reasoned about in spatial terms.The distance in space and distance in time (time continuity) are two facets of the same concept.Thus, the basic meaning of the past tense can be understood through the distance in space.Furthermore, most of image schema can be represented in highly abstracted simple diagrams, including the distance image schema.Through the TIME-AS-SPACE mapping, we can map the distance image schema in the space domain onto the time domain.See Figure 4: The TIME-AS-SPACE mapping is a set of ontological correspondences that map knowledge about space onto knowledge about time.Therefore, we can see from Figure 4, the temporal relation between the two spots A and O corresponds to the spatial relation between the two spots a and o.This distance image schema can help us have a better understanding of the past tense.
From the discussion above, this paper points out that the prototypical use of the past tense is to indicate the event/state that happened in past time.There is a distance between the past time at which the event/state happened and the present moment.The basic meaning of the past tense is to refer to the distance in time.The distance image schema is based on human's cognition of spatial relation and we assume that it is the original cognitive distance image schema.We will take this as our assumption and carry on further studies.

Metaphorical Extensions of the Past Tense
Taylor (2001) states that polysemy is not a property of words alone.The past tense also exhibits a cluster of related meanings (i.e.past time, counterfactuality and pragmatic softening), which can be counted as an instance of polysemy.The enlargement of the meanings of the past tense is a process of cross-domain mapping, in other words, metaphorical mapping.Based on his analysis, this paper adopts the metaphorical approach to the study of the past tense.In the following, the specific process of the metaphorical extensions of the past tense will be represented, including the extensions to the reality domain and the psychology domain.

The Past Tense in the Reality Domain
When people talk about things whose reality is not sure of, they tend to use the past tense.For example: (20) If they had left at nine, they would certainly be home by midnight.Traditionally, the past tense verbs in the above sentences are labeled as "abnormal uses" because they refer to either the event/state at the present moment or that in the future.Leech (1978: 10) regards the past tense in the above sentences as "used in dependent clauses to express HYPOTHETICAL meaning".The hypothetical past is mainly used in certain subordinate clauses, especially in if-clauses, and expresses what is contrary to the belief or expectation of the speaker (Quirk, et al., 1985: 188).However, his explanations are far from convincing.Joos (1964), Palmer (1974) and Yi (1999) all argue that the past tense denotes remoteness in time and reality, but none of them gives the specific process.Their studies are enlightening and my research has been greatly inspired by them.
This paper holds that the hypothetical past is a metaphorical extension of the prototypical use of the past tense.For these sentences all express hypothetical meaning, thus these sentences can be analyzed in the reality domain.Image schema are meaningful at the conceptual level precisely because they derive form the level of bodily experience, which is meaningful.Lakoff and Johnson (1980) both claim that image schema could serve as source domains for metaphorical mapping to structure more abstract concepts or domains.The mapping from the time domain to the reality domain goes as follows in Figure 5, in which " " is used to refer to the direction of mapping.
Figure 5.The mapping of the distance image schema from the time domain onto reality domain In this process, the potential similarities of the source domain (the time domain) and the target domain (the reality domain) are found during the radiation process.It is people's metaphorical thinking that makes people see the relationship between concepts and then produce the mapping from the concrete domain to the abstract domain.
Thus, when people talk about something unreal, the past tense is used.In the following, examples ( 20)-( 23) are repeated here as ( 24)-( 27): (24) If they had left at nine, they would certainly be home by midnight.
(25) I wish I were young again.
(26) If only I had listened to my English teacher.
(27) Just suppose someone was/were following us.
The past tense form as had in example (24), which is originally used to indicate a temporal distance, is now mapped onto the reality domain through cross-domain mapping.There is a distance between the event/state and reality.In example (24), had suggests that the wish is unreal.Therefore, when hearers are confronted with this "abnormal" use of the past tense, they realize that the speaker is actually expressing a counterfactual wish.The use of the past tense in conditional reminds the reader/hearer that the condition described in the subordinate clause is not true.Thus, the past tense in these cases marks dissociation from the truth of the proposition.The past tense form in the hypothetical past is used to give some suggestion, advice and sometimes there are implications in the sentences.Let's look at the above examples, sentence (24) indicates that "they did not leave at nine", example (25) suggests that "I am not young any more", sentence (26) implies that "I did not listen to my English teacher", example (27) actually implies that "there are no one following us".Therefore, we arrive at an interpretation that the so-called "hypothetical past" is a metaphorical extension of the prototypical use of the past tense.Based on the distance image schema, we can map the distance in the time domain onto the reality domain.Both Yi (1999) and Taylor (2001) state that the image schema of the past tense can be mapped onto the psychology domain, this paper adopts their claim.In the following, we will analyze the attitudinal past.

The Past Tense in the Psychology Domain
In daily conversation, we often come across another type of the past tense, which refers neither to past time nor to unreality.For example: It is clear, the verb form as Did and hope in sentence ( 28) has nothing to do with past time, because we can infer from the sentence that the subject of this exchange is most probably the present wishes of B. It has no suggestion of unreality, either.B does want a hand from A. Leech (1978) argues the use of the past tense in example ( 28) refers to the present feelings or thoughts of the speaker or hearer.According to Quirk, et al. (1972), the use of the past tense in example ( 29) is called the hypothetical past and that in example ( 30) is called the attitudinal past.Taylor (2001) regards the use of the past tense in (31) as pragmatic softener, which involves double metaphorization: the first is the TIME-AS-SPACE mapping; the second mapping applies the schema of distance and proximity to the domain of involvement.
Based on the previous studies, this paper argues that like the hypothetical past, the attitudinal past is also a metaphorical extension of the prototypical use of the past tense.In Figure 6, the distance image schema in the time domain is mapped onto the psychology domain with the help of the conceptual metaphor theory.Figure 6.The mapping of the distance image schema from the time domain onto the psychological domain The metaphorical mapping doesn't come from the similarities of objects themselves but from the co-effect of the objective world and man's thinking.It is people's metaphorical thinking that makes people see the relationship between concepts and produces the mapping from the time domain to the psychology domain.
The attitudinal past underlies many everyday expressions.Let's look back the examples that we have mentioned in the beginning of this section.In example ( 28), the present tense and the past tense, in this context, are actually interchangeable; but there is an important difference of tone between them.The present tense I hope... would seem rather brusque and demanding, which would make the request difficult to refuse without impoliteness.And the present tense in Do you want me might contain peremptory overtones, and would seem to say: Oh, it's you, is it?You always want something.The present tense makes requests direct and therefore leaves little room for the hearer to choose as he wishes.However, the use of the past tense in Did you want me conversation can keep the distance between participants, thus offering options for the hearer.The past tense can avoid a confrontation of wills and make the request indirect and therefore more polite.The same is true with example (29): It's time you were in bed.Quirk, et al. (1985, p. 188) regard the use of the past tense in example (29) as "hypothetical past", but we consider that it is a polite suggestion, a fossilized pattern to make the request indirect and more acceptable.Thus, the use of the past tense softens the request and leaves a bigger room of choice for the hearer.
To sum up, the essence of metaphor is to use one thing to understand and experience another thing.We can understand the attitudinal past by using the knowledge about the past time use of the past tense.In our daily life, if one is not familiar with another one, there is a special distance between them.Through the mapping from the time domain to the psychology domain, the temporal distance turns into the psychological distance between the speaker and hearer.This explanation is reasonable and convincing.Thus, we arrive at an interpretation that the so-called "attitudinal past" is a metaphorical extension from the prototypical use of the past tense.Palmer (1974, p. 39) states that present time muse be understood to mean any period of time that includes the present moment.It includes, therefore, "all time" as in:

The Prototypical Use of the Present Tense
(32) The sun rises in the east.
(33) Water boils at 1000 Centigrade.Palmer (1974) argues that past time excludes the present moment, while he claims present time is any period, short or eternal that includes the present moment.It is clear that there is a contradiction in Palmer's view of present time and past time, which makes people confused about the past tense and the present tense.Jespersen (1949) gives no clear definition of the present time, but he takes the present moment as a mathematical point that has no dimension, no length at all.Leech does not give a very specific definition of what the present time is, either.He equals the present moment of time to the moment of speech in his discussion of the present tense (Leech, 1978, p. 1).Because of the ambiguity of the concept of the present time, Leech, Jespersen and many other grammarians divide the uses of the present tense referring to the present moment into three types: the unrestrictive use, the instantaneous use and the habitual use.In this paper, present time equals to the present moment of speech that is the time of speaking.It is the reference point for both the present tense and the past tense in the time domain.(42) Whenever ammonia is added, the color changes to orange.
Traditionally these sentences are studied in the time level.Palmer (1974, p. 43) points out that the present tense in sentence (41) suggests that the actions happen in "all time".Comrie (2005, p. 39) claims that sentences with habitual aspectual meaning refer not to a sequence of situations recurring at intervals, but rather to a habit, a characteristic situation that holds at all times.In our point of view, the above explanations still fail to give a coherent and systematic explanation of the present tense.
We consider the uses of the present tense in the above sentences are simply metaphorical extensions of the prototypical use of the present tense.Thus, we map the proximity image schema in the time domain onto the objective reality domain (for convenience, we will use the reality domain instead of objective reality domain).In this process, the potential similarities of the time domain and the reality domain are found during the radiation process, which is the result of people's metaphorical thinking.People take it for granted that in English, the present tense is used to describe the future event/state.For instance: (43) Next Christmas falls on a Thursday.
(45) I get a lump sum when I retire at sixty-five.
Traditional grammarians consider these sentences typical examples of the present tense used to express future time.Palmer (1974) mentions two kinds of future in The English Verb: one is prediction, and the other is futurity.Prediction means that the future situation is scheduled or arranged, which implies that the artificial factor has a decisive influence on it.Futurity refers to the objective future situations, which excludes the effects of the volitive faculty.
As far as our point of view is concerned, the present tense used in the above sentences is simply another metaphorical extension of the prototypical use of the present tense.In Figure 11, the proximity image schema in the time domain is mapped on to the imaginary-reality domain.
Figure 9.The mapping of proximity image schema from the time domain to the imaginary-reality domain In Figure 9, B" (the event/state that will happen in the future) corresponds to B (the present time at which the event/state happens), O" (the imaginary reality) corresponds to O (the present moment).B" and O" are proximal in the imaginary domain.Thus, when people believe the event/state is sure to happen, the present tense is used.Or rather, when the present tense is used without referring to present moment but future time, the present tense convey the message that these events/states are sure to be true, at least the speaker/writer believes so.Therefore, the present tense in sentences ( 43)-( 45) are not indicators of time but the certainty of their happening.This is also true in conditionals.Now we can safely say that the present tense indicates proximal to reality, either objectively or imaginarily.Please read the following sentences: (46) I'll tell you if it hurts.
(47) When the spring comes, the swallows will return.
(48) Jeeves will announce the guests as they arrive.
In the dependent clauses above, the happenings referred to is not a prediction, but a fact that is taken as given.A conditional sentence has the structure: If X is a fact, then I predict Y. Thus, in the if clause, the present tense suggests factual certainty.
We believe that the present tense used to express the event/state which happens in the future, either in statements or conditionals, is the result of metaphorical extension through mapping that is based on the image schema of proximity.Thus, another meaning of the present tense, i.e. indicating the event/state being real or true in imagination, is constructed through the mapping from the time domain onto the imaginary reality domain.The inflectional tokens of the present tense, -0 or -(e)s, originally a marker of temporal proximity in the time domain and later a marker of proximity in the reality domain, are now mapped from the time domain onto the imaginary reality domain.Therefore, the temporal proximity is changed into the proximity in the imaginary domain indicating reality or truthfulness in imagination.

The Present Tense in the Psychology Domain
Under certain circumstances, the present tense is used to refer the event/state that happens in the past, as instances of sentences ( 49)-( 51): (49) Last week I'm in the sitting-room with the wife, when this chap next door staggers past and in a drunken fit throws a brick through our window.
(50) The ten o'clock news says that it's going to be cold.
(51) Brahms is the last great representative of Germen classicism.Leech (1978, p. 6-8) regards the present tense in examples ( 49)-(51) as "HISTORIC PRESENT" or "HISTORICAL PRESENT".According to Leech (1978), it is "historic/historical", because the event/state happened in the past, and it is "present", because the present tense is used and the present tense makes the event/state more vivid.Quirk, et al. (1985) claim that there are three kinds of the historical present.The first kind describes the past events as if they were going on at the present moment: it conveys something of the dramatic immediacy of an eye-witness account (Quirk, et al., 1985, p. 181).The so-called historic present is a characteristic of a popular narrative style, which can be seen in example (49).
The second kind is found with verbs of communication.Such verbs include understand, hear and learn, which refer to the receptive end of the communication process, like example (50).The implication of the present tense seems to be that although the communication event took place in the past, its result (the information communicated) is still operative (Quirk, et al., 1985, p. 181).According to Quirk, et al. (1985), the third kind refers to writers, composers, artists, etc. and their extant works, which suggests that people are still alive through their works.The present tense can be even used without respect to any particular work, like example (51), for general artistic characterizations of the author.Although Quirk, et al. represent the various kinds of the historic present, they do not offer a convincing and unified explanation.
This paper holds that the present tense used in the above sentences is a metaphorical extension of the prototypical use of the present tense to the psychology domain.In Figurine 10, the proximity image schema in the time domain is mapped onto the psychology domain.In this figure, O"' (realness and vividness) corresponds to O (the present moment), B"' (the event/state that happened in the past) corresponds to B (the present time at which the event/state happens).The proximity in the time domain is now mapped onto the psychology domain.When the speaker or writer wants to make the happenings sound more real or vivid, the present tense is used.Or rather, when the present tense is used to describe past happenings, it achieves the effect that the past happenings are portrayed as if they were taking place at the present moment.
Let us look back at the sentences we mentioned in the beginning of this section, example (49) seems to be a scene in a movie that is running on; example (50) suggests that the news "speaks" at the present time; and example (51) makes people think of Brahms as a composer still living through his compositions.All the verbs in these sentences can be replaced by the past tense forms, but the effect would be different.Thus, another metaphorical extension of the present tense (i.e.indicating vividness) is constructed through the interplay of the time domain and the psychology domain.The inflectional tokens of the present tense, -0 or -(e)s originally a marker of temporal proximity in the time domain is mapped onto the psychology domain.

Conclusion
In this paper, we have made a systematic study of the English tense from the perspective of conceptual metaphor theory under the guidance of cognitive linguistics.We have first reviewed some analysis of the past tense and the present tense by some scholars.Most of the previous studies on the past tense and the present tense confine their attention to establishing a relationship of one-to-one correspondence between time and the event/state, therefore many uses which are contradictory to their definitions are termed as "special" or "abnormal" uses, which undoubtedly weakens their interpreting power.Despite the demerits, the previous studies give us some enlightenment.The metaphorical approach to the English tense can overcome the defects of the previous studies and give a unified explanation to the various uses of the past tense and the present tense.Then we have built up a framework for the present study by the conceptual metaphor theory, including some related concepts, such as, image schema and cross-domain mapping.
This thesis is an attempt to study the past tense and the present tense from a metaphorical perspective.We have mainly discussed the prototypical use and metaphorical extensions of the past tense.We have tried to reveal the metaphorical mapping process of the past tense and therefore to get a more reasonable and systematic interpretation of the past tense.Based on the preceding researches, this paper holds that the past tense, originally indicating temporal distance, extends its meaning to the reality domain and the psychology domain.The hypothetical past is used to express counterfactuality indicating a distance from reality in the reality domain, to give some suggestions.The attitudinal past is used to express politeness and indirectness indicating a distance between the speaker and hearer in the psychology domain.All these are realized through cross-domain mapping based on the image schema of distance, which is extracted from the prototypical use of the past tense in the time domain.
With the same approach, we have discussed the different uses of the present tense.The present tense originally expresses temporal proximity.Based on the image schema of proximity abstracted from the prototypical use of the present tense, features of the present tense in the time domain are mapped onto the reality domain, the imaginary reality domain, and the psychology domain.Thus, the present tense is used to express truthfulness and reality indicating a proximity to reality, to express certainty and sureness of the happenings indicating a proximity to imaginary reality, and to bring about the effect of vividness indicating a proximity to psychological realness and vividness.With the help of metaphorical mapping, the various uses of the present tense gain a unified meaning: proximity.
It must be pointed out that the past tense in the psychology domain highlights its property of politeness and indirectness while the present tense in the psychology domain highlights its property of vividness and realness.
What's new about this paper is that tense is analyzed with the help of the concept of metaphor.The metaphorical extensions are analyzed by mapping the image schema in the time domain onto other domains.This paper also has some theoretical importance.To treat the different uses of the past tense and the present tense as a metaphorical extensions broadens the research scope of metaphor study.The research reveals the cognitive process of how people extend the prototypical use of the past tense and that of the present tense, which reflects the universal mechanism of how human beings get knowledge, that is, from known to unknown.
This paper is especially meaningful to the teaching and learning of the English tense in China.The traditional grammar books never provide a coherent and systematic explanation to the past tense and the present tense, and teaching about tense was always focused on mere time sphere with many exceptions that confuse both teachers and learners.In this study, to regard the past tense as distance in the time, reality and psychology domains, the present tense as proximity in the time, reality, imaginary reality and psychology domains can be accepted more easily and is helpful for the acquisition of tense.In addition, we have offered a clear and comprehensive process of the metaphorical extensions, and this is easy for students to understand and to use the English tense.

Suggestions for Future Study
This paper is just a tentative exploration into a unified study of the past tense and the present tense.Due to the limited time and resource, there certainly exist points which need improvement.Further study can also be carried out from other perspectives and there is a great deal of work to do as for the pragmatic functions of the past tense and the present tense for which only a small space is given in this study.And further researches can also be made for the study of the English tense in discourse.Though this study has some glittering points, it still unavoidably has some limitations.In the future, more investigations should be devoted to English tense study.

( 7 )
If I had enough time, I would buy the bigger one.(If-conditionals) (8) I wish I knew the answer.(wishes and desires) (9) Suppose we went to see him.(Suppositions and suggestions)

Figure 1 .
Figure 1.The mapping from the space domain onto time domain and the involvement domain

Figure 4 .
Figure 4.The mapping of the distance image schema from space domain onto the time domain

(
21) I wish I were young again.(22) If only I had listened to my Math teacher.(23) Just suppose someone was/were following us.

(
28) A: Did you want me?B: Yes, I hoped you would give me a hand with painting.(29) It's time your were in bed.(30) I wonder/wondered if you could help me.(31)Excuse me, I wanted to ask you something.

Figure 8 .
Figure 8.The mapping of the proximity image schema from the time domain to the reality domain

Figure 10 .
Figure 10.The mapping of the proximity image schema from the time domain onto the psychology domain TIME IS A LIMITED RESOURCE (You don't use your time profitably.)TIME IS A VALUABLE COMMODITY (I don't have the time to give you.)TIME IS MONEY, TIME IS A LIMITED RESOURCE and TIME IS A VALUABLE COMMODITY are