 Rule seven of the first discourse is dedicated to the notion of definition, its conditions and reconfiguration into an ishraqi principle (PI, §§13–5; Ziai 1990, 77–114). Suhrawardi begins by rejecting the Peripatetic theory of definition that he criticizes for the inductive approach it advocates as a foundation for scientific knowledge and demonstration. He uses logical and semantic arguments to question its ‘essentialist’ definition (Aristotelian) on which Avicenna’s own ‘complete definition’ depends. He rejects the claims that it is possible to obtain a complete definition able to encompass all the essential constituents needed to lead to the knowledge of that which is previously unknown and in need of a definition. Suhrawardi writes that “it is clear that it is impossible for a human being to construct an essential definition in the way the Peripatetics require—a difficulty which even their master [Aristotle or Avicenna] admits. Therefore, we have definition only by means of things that specify by conjunction” (PI, §15). Suhrawardi insists that a definition should enumerate, in some kind of unitary formula, all the essential constituents of the described object. Therefore, he includes elements of definition by extension (enumeration of members of a ‘class’) and of definition by intension (enumeration of defining property or properties), for example, that “the essence of man (which is the truth underlying the symbol ‘man’), is a thing which is only recoverable […] in the subject. This act of ‘recovery’ is the translation of the symbol to its equivalent in the consciousness or the self of the subject” (Ziai 1990, 127). For Street (2008, 178), what he calls his ‘anti-essentialism’, or the inability to graps essences discursively, as he accepts the Platonic forms, does not rest on his logic. Suhrawardi explains his ‘conceptualist’ notion of definition at greater length in his Paths and Havens (Suh. 2006, 83, 90–100). His epistemological critique of the Peripatetic theory of definition is undoubtedly inspired by Abu al-Barakat al-Baghdadi’s own critical evaluation of the Isagoge which was developed in his al-Mu‘tabar (1939, vol. 1, 55–7; cf. Ziai 1990, 183–4), but also by Suhrawardi’s own understanding of the epistemic role of self-knowledge as presence. 