531. The middle forms outside the present-system (for which there is a special passive inflection: see below, 768 ff.), and sometimes also within that system, are liable to be used likewise in a passive sense.
532. Tense. The tenses are as follows: 1. a present, with 2. an imperfect, closely related with it in form, having a prefixed augment; 3. a perfect, made with reduplication (to which in the Veda is added, 4. a so-called pluperfect, made from it with prefixed augment); 5. an aorist, of three different formations: a. simple; b. reduplicated; c. sigmatic or sibilant; 6. a future, with 7. a conditional, an augment-tense, standing to it in the relation of an imperfect to a present; and 8. a second, a periphrastic, future (not found in the Veda).
a. The tenses here distinguished (in accordance with prevailing usage) as imperfect, perfect, pluperfect, and aorist receive those names from their correspondence in mode of formation with tenses so called in other languages of the family, especially in Greek, and not at all from differences of time designated by them. In no period of the Sanskrit language is there any expression of imperfect or pluperfect time — nor of perfect time, except in the older language, where the "aorist" has this value; later, imperfect, perfect, and aorist are so many undiscriminated past tenses or preterits: see below, under the different tenses.
533. Mode. In respect to mode, the difference between the classical Sanskrit and the older language of the Veda — and, in a less degree, of the Brāhmaṇas — is especially great.
a. In the Veda, the present tense has, besides its indicative inflection, a subjunctive, of considerable variety of formation, an optative, and an imperative (in 2d and 3d persons). The same three modes are found, though of much less frequent occurrence, as belonging to the perfect; and they are made also from the aorists, being of especial frequency from the simple aorist. The future has no modes (an occasional case or two are purely exceptional).
b. In the classical Sanskrit, the present adds to its indicative an optative and an imperative — of which last,
