 To define the soul as operating through an instrument, i.e., the body “in an ambiguous sense”, as Avempace does (IB-S1a: 29. 2), implies it is autonomous. Avempace defines the soul also as first entelechy (istikmal), as opposed to the last entelechy of the geometer, i.e., its being geometer in act. Soul appears as an incorporeal substance, of highest rank. The science of soul is considered by Avempace as superior to physics and mathematics, only inferior to metaphysics. Avempace is not disturbed by Aristotle’s hylemorphic view of the soul which he may have known. He affirms that all philosophers agreed that the soul is a substance and portrays Plato as the adequate source: