 As that last interpretive remark suggests, this passage demands commentary and commentators disagreed about how it was to be understood. (For a classic survey, see Brentano 1992.) Broadly speaking, there were two views. The first held that the agent intellect was separate from each human mind, such that the intelligible forms “flow” from this immaterial entity into the mind to produce an act of understanding. This was the view held, in two quite different forms, by Ibn Sīnā (Avicenna) and Ibn Rushd (Averroës) (1126–1198). Such a view implies that there is only one agent intellect, common to all human beings, which may or may not be identified with God himself. (When it is identified with God, this view closely resembles the Augustinian doctrine of divine illumination.) The alternative idea, vigorously defended by Aquinas, held that both the agent intellect and the potential intellect are aspects of the human mind. Even among those who held that latter view, there were different ways in which the agent intellect was thought to produce knowledge. In some versions of the doctrine (such as Aquinas’s) the agent intellect was thought to abstract the intelligible forms from the images produced by the senses. In other versions, the input of the senses was little more than the occasion on which the agent intellect drew on its own innate resources, in the process of which the mind could be thought of as enlightened by God. Thomas of York (d. ca. 1260), for instance spoke openly in this context of innate ideas and of a knowledge that came “from above and not from the senses” (Bowman 1973: 265).