Avicenna set an influential example for Aquinas. Works of his which circulated in Latin translation as De Anima (On the Soul) and Metaphysica (Metaphysics) are not commentaries on Aristotle's texts, but paraphrases of them; and Avicenna did not hesitate to introduce non-Aristotelian positions. Example to use in a term paper: Aquinas' astronomical views had prompted Moses Maimonides in the twelfth century to remark that whereas Aristotle is reliable for what is located beneath the "sphere of the moon," he is no guide on what is above that sphere. A roughly parallel attitude with respect to Aristotle would mark the early work of Aquinas. In his De Ente et Essentia (On Being and Essence, 1253) for instance, Aquinas would produce an incontrovertibly "Aristotelian" manual, but like Maimonides and Avicenna before him, he would neither accept the restrictions of a mere commentator nor refrain from the most fundamental doctrinal adjustments. Aristotle made grammatical and logical distinctions between the use of the verb to be in its existential and in its merely copulative functions and considered existence as philosophically irrelevant. To say man, one man, or existing man is to engage in merely verbal variations; such must be the case if philosophy deals solely with universal essences and not with the singulars in which essences are given only a transitory reality. In Aristotle's thought the essence of man is eternal and a suitable subject for philosophical investigation, whereas Socrates comes into and out of reality, a suitable subject for history - than which even poetry is "more philosophical." In his eternal cosmos Aristotle counted the singular instantiation of an eternal essence as of no philosophical value beyond providing an object of sensation from which, by the action of intellect, one can abstract the necessary, philosophically significant essence.
In contrast, Aquinas would hold that actually to be is the ultimate ground of reality, of value, and of fulfillment. Thus it seems legitimate to speak of De Ente et Essentia as an independent essay in the Peripatetic tradition that has been written as an Avicennian paraphrase rather than a phrase-by-phrase commentary. This early style would shift in the mature Aquinas to one more redolent of Averrees. Those later, formal expositions of Aristotelian works can be called "Averroistic" in their style, if not in their content. They proceed by the sort of painstaking, phrase-by-phrase exegesis of the Philosopher's text that earned ibn Rushd his honorific title of "the Commentator." Aquinas, despite his sensitivity to the value of literary styles and of philosophical materials, would remain his own master, transforming the materials he adopted from the great Greeks and Muslims. You may focus your essay on his purpose as a master of theology was consistently a theological one, no matter how austerely he distinguished between what can be known through native rationality and what can be grasped only through faith. In his own view, as he would state it in In Librum Boethii de Trinitate Expositio (Exposition of Boethius's On the Trinity, 1257-1258), he was "transforming the water of philosophy into the wine of theology," an evocation of the miracle of Cana.