Строй современного английского языка

Mood and Tense 111
c ertain). We can illustrate this use by examples of the following kind: The House will know that... (used, for example, in parliament speeches).
The sources of this use seem clear enough. The original meaning of such sentences seems to have been, approximately, this: 'It will appear (afterwards) that you know', etc.
In a similar way the future perfect can be used to denote an action which is thought of as finished by the time of speaking and represented as probable. This is seen in such sentences as the following: ...You'll not have spoken to her mother yet? (LINKLATER), which is equivalent to Probably you have not spoken to her mother yet? The origin of this use is analogous to that of the future as shown above. The sentence just quoted would have meant, 'It will appear (afterwards) that you have not spoken', etc. In the following example the future-in-the-past and the future-perfect-in-the-past are used in this way: I made for my lodgings where by now Melissa would be awake, and would have set out our evening meal on the newspaper-covered table. (DURRELL) It is the adverbial modifier by now which makes the meaning perfectly clear.
In this way both the future and the future perfect can acquire a peculiar modal colouring. As in some previous cases, we ought to look for certain patterns, including, probably, lexical as well as grammatical items, in which this modal colouring is found. ¹
An interdependence between mood and tense which has a much wider meaning may be found if we analyse the system of tenses together with that of moods. When the question arises, how many tenses there are in the Modern English verb and what these tenses are, examples for that kind of analysis are always taken from the indicative mood. ² Indeed, it is only in this mood that we find the system of tenses fully developed. In no other mood, however we may classify those other moods, shall we find the same system of tenses as in the indicative. The cause of this is evident enough: it is the indicative mood which is used to represent real actions, and it is such actions that are described by exact temporal characteristics. As to those actions which do not take place in reality but are thought of as possible, desirable, etc., they would not require a detailed time characteristic. Time is essentially objective, while all moods except the indicative are subjective.
¹ A similar phenomenon is found in Russian, as when a verb in the future form (chiefly the verb быть) is used to denote something referring to the present, with a peculiar modal colouring, e.g. До меня верст пять будет (ТУРГЕНЕВ), А кто ж такая будете? (Idem) See В. В. Виноградов, Русский язык, стр. 575.
² This is of course also true of Russian grammar: the analysis of the three tenses of the Russian verb is always based on material provided by the indicative mood.

112 The Verb: Mood
Things are quite clear in the sphere of the imperative. Since its basic meaning is an appeal to the listener to perform an action it is obviously incompatible with the past tense. A difference might exist between present and future, in the sense that the speaker might appeal to the listener to perform the action either immediately or at some future time. However, no such difference is found in the imperative forms either in English or in most other languages. ¹
As to the moods expressing condition, desire, and the like, the problem of tense is somewhat more complicated. If we compare the two well-known types of conditional clauses:

1. 
   If he knew this, he would come,
   
2. 
   If he had known this, he would have come,
   

we are faced with a complexity of interwoven problems. Evidently our interpretation of these phenomena will depend on our treatment of the forms knew, would come, had known, and would have come (see above).
If we take the view that knew is the past indicative which in this context is used to express an unreal action in the present, and would come the future-in-the-past, which in this context is used to express an unreal consequence in the present, there is nothing more to be said about the tense or any other category appearing in this type of sentence.
In a similar way, if we take the view that had known is the past perfect indicative which in this context is used to express an unreal condition in the past, and would have come the future-perfect-in-the-past which in this context is used to express an unreal consequence in the past, there is nothing more to be said about it.
If, on the other hand, we interpret the forms knew, had known, would come, and would have come as special mood forms, we shall have to characterise the difference between knew and had known and that between would come and would have come in another way. We shall have to find an answer to the question, what grammatical category underlies the oppositions:
knew — had known
would come — would have come.
Here we are faced with a peculiar difficulty. If we judge by the means of expression (the auxiliary have is used in the second
¹ The Latin language does distinguish between a present imperative, e.g. dic 'say!' (now), and a future imperative, e.g. dicito! 'say!' (afterwards). But this distinction is rarely made use of.

Mood and Tense 113
column, but not in the first) we shall compare this opposition to
that between
knows — has known
will know — will have known,
and reach the conclusion that the opposition is based on the category of correlation, as defined above. In that case there would not be any tense category at all in the system of these moods.
But it might also be argued that, according to meaning, the opposition is one of tense (present vs. past). In that case there would be the category of tense in these moods but no correlation.
The choice between these two views remains arbitrary. For the sake of the unity of the system it would seem preferable to stick to the view that wherever we find the pattern "have + second participle" it is the category of correlation that finds its expression in that way.
To sum up the whole discussion about the categories of the verb found in conditional sentences, the simplest view, and the one to be preferred is that we have here forms of the indicative mood in a special use. Another view is that we have here forms of special moods, and that they are distinguished from each other according to the category of correlation.
If we endorse the view that there are no homonymous forms in the English verb a sentence like if he knew this he would come will be interpreted as containing the past tense of the verb know and the future-in-the-past of the verb come, the very existence of mood as a special grammatical category in Modern English becomes doubtful, since it will appear lacking any specific means of expression. This might be the way to "cut the Gordian knot" of problems posed by the analysis of modal meanings in the verb.
This ends our discussion of aspect, tense, correlation, and mood.