  In a complex discussion, Khayyam presents his views on the relationship between the subject, predicate, and attributes using a mixture of original insight and Aristotelian precedent. Dividing the attributes into two parts, essential and accidental, he discusses essential and accidental attributes and their subdivisions such as abstract (i‘tibārī) and existential (wujūdī) (Risālah fi'l-wujūd, 102). Continuing the argument in “The Necessity of Contradiction, Determinism, and Subsistence” (Ḍarūrat al-taḍād fi'l-‘ālam wa'l-jabr wa'l-baqā‘, 164), Khayyam proposes that conceiving essential attributes necessitates the presence of a priori (badawī) concepts such as “animality which is an essential attribute of man.” 