The impetus theory of the Vaisesikas
In Europe, the Impetus Theory of Motion was developed in the fourteenth century, although ideas resembling such a theory appeared in the writings of John Philoponus (sixth century A. D.) and, further back, in those of Hipparchus. In India, the basic principles of the theory appeared during the formulation of the Vaiśeṣika aphorisms (third century B. C.), and a fully developed Impetus Theory is recognized in Praśastspada's Bhāṣya (fifth century A.D.). The paper briefly discusses how the inadequacy of the Aristotelian dynamical principle led to the Impetus Theory in Europe. The Vaiśeṣika concept of motion, as developed by Praśastapāda, is then discussed with special reference to the various forces causing motion, e. g. abhighāta nadana, gurutva, dravatra and saṃskāra. The term saṃskāra (impetus) of which the Vaiśeṣikas recognize three types, e.g. vega, bhāvanā and sthilisthāpaka, is the cause of uninterrupted continuity of motion in a fixed direction even when the initial force ceases to act, and thus hols the key to the Vaiśeṣika Impetus Theory, It is shown that this saṃskāra or vega is the nearest approach to our modern conception of momentum, The interplay of various kinds of forces and the part played by saṃskāra in maintaining the motion of bodies when all forces cease to act are explained by three illustrations, e. g. the motion of the pestle and the mortar, the motion of a javelin discharged by the hand and the motion of a body catapulted from a machine.
Indian Journal of History of Science, Vol. 1, no. 1 (1996), 34–35.