 A is per se1 with respect to B iff ‘A’ is in the account which gives the essence of B. Note that Aristotle does not say that A belongs to all B (e.g., ‘hair’ occurs in the definition of bald, but ‘having hair’ does not belong to a bald person), yet it is presupposed by the use Aristotle makes of it. Aristotle allows that there are immediate statements of the form, A belongs to no B. Mathematical examples: ‘line’ is in the definition of triangle, ‘point’ is in the definition of line.