602. In a small minority of verbs, the present-stem is identical with the root. Then there are besides (excluding the passive and causative) seven more or less different methods of forming a present-stem from the root, each method being followed by a larger or smaller number of verbs. These are the "classes" or "conjugation-classes", as laid down by the native Hindu grammarians. They are arranged by the latter in a certain wholly artificial and unsystematic order (the ground of which has never been discovered); and they are wont to be designated in European works according to this order, or else, after Hindu example, by the root standing at the head of each class in the Hindu lists. A different arrangement and nomenclature will be followed here, namely as below — the classes being divided (as is usual in European grammars) into two more general classes or conjugations, distinguished from one another by wider differences than those which separate the special classes.
603. The classes of the First or non-a-Conjugation are as follows:
I. The root-class (second class, or ad-class, of the Hindu grammarians); its present-stem is coincident with the root itself: thus, अद् ad eat; इ i go; आस् ās sit; या yā go; द्विष् dviṣ hate; दुह् duh milk.
II. The reduplicating class (third or hu-class); the root is reduplicated to form the present-stem: thus, जुहु juhu from √हु hu sacrifice; ददा dadā from √दा dā give; बिभृ bibhṛ from √भृ bhṛ bear.
III. The nasal class (seventh or rudh-class); a nasal, extended to the syllable न na in strong forms, is inserted before the final consonant of the root: thus, रुन्ध् rundh (or रुणध् ruṇadh) from √रुध् rudh obstruct; युञ्ज् yuñj (or युनज् yunaj) from √युज् yuj join.
