None of these expressions imply more than a single action; in other words, they have no relation to any second action occurring simultaneously with them, before them, or after them.—I am speaking now, I spoke yesterday, I shall speak to-morrow. Of course, the act of mentioning them is not considered as an action related to them in the sense here meant.
By considering past, present, or future actions not only by themselves, but as related to other past, present, or future actions, we get fresh varieties of expression. Thus, an act may have been going on, when some other act, itself an act of past time, interrupted it. Here the action agrees with a present action, in being incomplete; but it differs from it in having been rendered incomplete by an action that has past. This is exactly the case with the—
4. Imperfect.—I was reading when he entered. Here we have two acts; the act of reading and the act of entering. Both are past as regards the time of speaking, but both are present as regards each other. This is expressed, in English, by the past tense of the verb substantive and the present participle, I was speaking; and in Latin and Greek by the imperfect tense, dicebam, ἔτυπτον.
5. Perfect.—Action past, but connected with the present by its effects or consequences.—I have written, and here is the letter. Expressed in English by the auxiliary verb have, followed by the participle passive in the accusative case and neuter gender of the singular number. The Greek expresses this by the reduplicate perfect: τέ-τυφα=I have beaten.
6. Pluperfect.—Action past, but connected with a second action, subsequent to it, which is also past.—I had written when he came in.
7. Future present.—Action future as regards the time of speaking, present as regards some future time.—I shall be speaking about this time to-morrow.
8. Future præterite.—Action future as regards the time of speaking, past as regards some future time.—I shall have spoken by this time to-morrow.
These are the chief expressions which are simply determined by the relations of actions to each other, and to the time of speaking, either in the English or any other language. But over and above the simple idea of time, there may be others superadded: thus, the phrase, I do speak means, not only that I am in the habit of speaking, but that I also insist upon it being understood that I am so.
Again, an action that is mentioned as either taking place, or as having taken place at a given time, may take place again and again. Hence the idea of habit may arise out of the idea of either present time or aorist time.