________________ -2 Prasastapadabhasya or Padarthadharma-Sangraha-- : The Vaisesika Sutras of Kanada are the first available and authentic source of the Vaisesika system. The text-book of these aphorisms presents basic principles of this system and expounds the nature of six categories (Padarthas ) viz. Dravya ( substance ), Guna (quality ), Karma (motion ). Samanya ( Genus ) Visesa (species) and Samavaya (Inherence). However the credit of an eleborate delineation of Vaisesika system certainly goes to Prasastapada also known as Prasastadeva, Prasastamati or Prasastakaradeva. His monumental work Padarthadharma-Sangraha, though known as Prasastapada-bhasya is not a commentary on VS of Kanada. It is an independent treatise on Vaisesika system based on the aphorisms of Kanada. Generally, it is contended that Prasastapada was either a predecessor or a contemporary of Vasubandhu--the teacher of Dinnaga and thus he probably belonged to the fourth century A.D. It seems that Prasastapada has presented his views so as to meet some of the concepts of Buddhist philosophy, though he rarely enters into any controversy. PDS is a systematic work and so the pattern adopted by Prasastapada in this treatise, almost became a model for the later writers of manuals on Nyaya and Vaisesika systems. In VS of Kanada, the three categories, Samanya, Visesa and Samavaya were of subjective reality (Samanya visesa iti buddhyapeksam-VS 1-11-3). Prasastapada established their external objective realities and in this way gave a new turn to the realistic system of Nyaya-Vasesika philosophy. He also increased the number of qualities to twenty four from seventeen as given by Kanada. In this monumental work, Prasastapada has not only elaborated the essence of the six categories but has also dealt with in full a number of important tenets of Vaisesika system, such as theory of Atoms (Paramanuvada ), intricacies about the nature of relation (Sambandha), similarities and differences among categories, theory of creation and destruction of three substances (earth, water and air ), theory of causation, nature of Self, the problem about an explicit concept of the quality number' (Sankhya), Pakajaprakriya, nature of cognition and judgement, definitions and number of Pramanas and the role of merits and demerits in relation to the attainment of liberation. Some of the conclusions as arrived at by Prasastapada, became pet theories of Vaisesikas in later period. Thus, for example, Prasastapada says with conviction that Self is imperceptible. Its existence is proved only by inference. Similarly, according to Prasastapada, inherence ( samavaya) is not directly per