 The third discourse presents sophistical refutations of errors uncovered in the formal and material logic of Peripatetic logic (an epitome of the Sophistical Refutations of the Organon) (PI, §§34–106). The third section deals with a number of his ishraqi judgements against a number of Peripatetic issues of physics and metaphysics (see 3. and 4.). It also serves to establish certain “technical terms” (substance and accident, necessity and contingency, cause, and possible and impossible infinities) (PI, §52–5), and on ‘beings of reason’ (i‘tibarat ‘aqliyya) (existence, necessity, etc.) (PI, 56–68). Suhrawardi also revisits the classical theory of the categories, adopting a reduced non-Peripatetic classification of five categories: ‘substance’ (jawhar), ‘quantity’, ‘quality’, ‘relation’ (similar to Stoic reduction of categories to those four, cf. Walbridge 1996, 527), to which he adds ‘motion’ (absent in Ibn Sahlan), the latter four being accidental categories (PI, §71; Suh. 1993a, 4–12, 284–93; Ziai 1990, 72 n.2, 73 n.3; Beidokhti 2018, 394–400). An ‘intensity’ (or perfection) is predicated of those five categories, such that the degree of intensity (with its corollary ‘weakness’) of light becomes a property of substances as well as of accidents (Ziai 1990, 73–5). 