If Avicenna had said that the extrinsic active intellect came in only when there was question of our mastering difficult and subtle truths, this argument would not hold against him. It holds so far as he supposes the agency of this intellect indispensable to our understanding things even the simplest and most obvious. Cf. Ueberweg, History of Philosophy, I, p. 413: "Avicenna distinguishes a twofold development of our potential understanding into actuality, the one common, depending on instruction, the other rare, and dependent on immediate divine illumination."

Of God and His Creatures: 2.76