 In spite of the metaphysical differences which distinguished the various schools of thought, both Buddhist and Brahmanical, all thinkers came to use a naive realist’s ontology to specify the states of affairs in connection with the canonical syllogism. According to this view, the world consists of individual substances, or things (dravya), universals (sāmānya) and relations between them. The fundamental relation is the one of occurrence (vṛtti). The relata of this relation are known as substratum (dharmin) and superstratum (dharma) respectively. The relation has two forms: contact (saṃyoga) and inherence (samavāya). So, for example, one individual substance, a pot, may occur on another, say the reason, by the relation of contact. In this case, the pot is the superstratum and the reason is the substratum. Or, a universal, say treeness, may occur in an individual substance, say an individual tree, by the relation of inherence. Here, treeness, the superstratum, inheres in the individual tree, the substratum. The converse of the relation of occurrence is the relation of possession. In addition, the relation of pervasion (vyāpti), or what had also been referred to as the relation of indispensability (a-vinā-bhāva), can also be defined in terms of the occurrence relation: one superstratum pervades another just in case wherever the second occurs the first occurs. The converse of the pervasion relation is the concomitance relation (anvaya) and its contrapositive is exclusion (vyatireka). As a result of these relations, the world embodies a structure: if one superstratum, designated as H, is concomitant with another superstratum, designated as S, and if a particular substratum, say p, possesses the former superstratum, then it possesses the second. This structure is the one which underlies the classical Indian canonical syllogism.