Although William of Auvergne, bishop of Paris from 1228 to his death in 1249, criticized Avicenna severely, he also adopted many philosophical positions of Avicenna. In a recently published article, I emphasized William's considerable debt to the philosophy of Avicenna, and in a still-to-be-published article I pointed out how William was indebted to Avicenna for his view of what it is to be a human being, and especially for his view of the spirituality of the human soul. For much of his lengthy work, De anima, William follows Avicenna's philosophy as he found it in the great Islamic thinker's Liber de anima, seu sextus de naturalibus; not, of course, without serious criticism on many points. In chapter 5, however, of his De anima, William rather abruptly introduces a historical concept of human nature, which is closer to that of Augustine than of Avicenna or Aristotle, in place of the philosophical concept of human nature, which he derived largely from Avicenna, whom he often confused with the real Aristotle. In introducing such a historical concept of human nature or of the nature of the human soul, William raises several rather intriguing problems, which I want to discuss in this paper. First, he raises a question about how the various historical states of human nature are to be conceived and how they are to be combined with the philosophical concept of nature that he derives from Avicenna. Second, he raises a question about how he can, while claiming to proceed exclusively by means of philosophical proofs, introduce such topics as the original state in which Adam and Eve were created, the original sin by which they fell and which they passed on to the rest of the human race, and Christian baptism by which the harm stemming from their sin can be undone. Finally, William speaks about the soul's state of natural happiness as opposed to the state of glory, and though his treatment of these states is rather brief, it raises a further question about how William envisaged these states and their relationship to each other. Hence, the paper will have three parts: the first on the present and past states of human nature of which William speaks and on their relationship to the philosophical concept of human nature, the second on how William introduces into what he claimed was strictly philosophical such apparently theological topics, and the third on how William understands the relation between the soul's state of natural happiness and the state of glory.