soul, arousing it to the exercise of its higher functions, and then returning to its divine source. This theistic interpretation of Aristotle was strongly opposed by the commentator Themistius who considers that Alexander forces the statement of the text out of its natural meaning and draws an unwarrantable deduction from the two sentences "these differences must be present in the soul," and "this alone is immortal and eternal." It seems, however, that Alexander's interpretation played an important part in the formation of neo-Plantonic theory, and it certainly is the key to the history of Muslim philosophy, and is not without its importance in the development of Christian mysticism.
The neo-Platonic school was founded by Ammonius Saccas, but really takes its definite form under Plotinus (d. 269 A.D.). In sketching in brief outline the leading principles of this system we shall confine ourselves to the last three books of the Enneads (iv-vi) as these, in the abridged form known as the "Theology of Aristotle" formed the main statement of neo-Platonic doctrine known to the Muslim world. In the teaching of Plotinus God is the Absolute, the First Potency (Enn. 5. 4. 1.), beyond the sphere of existence (id. 5. 4. 2.), and beyond reality, that is to say, all that we know as existence and being is inapplicable to him, and he is therefore unknowable, because on a plane which is altogether beyond our thought. He is unlimited and infinite (id. 6. 5. 9.) and consequently One, as infinity excludes
