The only path to scientific human psychology is through comparative psychology.  It is a long and wearisome path, but it leads to truth.

Is there, then, a vast spiritual existence pervading the universe, even as there is a vast existence of matter pervading it—­a spirit which, as a great German author tells us, “sleeps in the stone, dreams in the animal, awakes in man?” Does the soul arise from the one as the body arises from the other?  Do they in like manner return, each to the source from which it has come?  If so, we can interpret human existence, and our ideas may still be in unison with scientific truth, and in accord with our conception of the stability, the unchangeability of the universe.

To this spiritual existence the Saracens, following Eastern nations, gave the designation “the Active Intellect.”  They believed that the soul of man emanated from it, as a rain-drop comes from the sea, and, after a season, returns.  So arose among them the imposing doctrines of emanation and absorption.  The active intellect is God.

In one of its forms, as we have seen, this idea was developed by Chakia Mouni, in India, in a most masterly manner, and embodied in the vast practical system of Buddhism; in another, it was with less power presented among the Saracens by Averroes.

But, perhaps we ought rather to say that Europeans hold Averroes as the author of this doctrine, because they saw him isolated from his antecedents.  But Mohammedans gave him little credit for originality.  He stood to them in the light of a commentator on Aristotle, and as presenting the opinions of the Alexandrian and other philosophical schools up to his time.  The following excerpts from the “Historical Essay on Averroism,” by M. Renan, will show how closely the Sarscenic ideas approached those presented above: 

This system supposes that, at the death of an individual, his intelligent principle or soul no longer possesses a separate existence, but returns to or is absorbed in the universal mind, the active intelligence, the mundane soul, which is God; from whom, indeed, it had originally emanated or issued forth.

The universal, or active, or objective intellect, is uncreated, impassible, incorruptible, has neither beginning nor end; nor does it increase as the number of individual souls increases.  It is altogether separate from matter.  It is, as it were, a cosmic principle.  This oneness of the active intellect, or reason, is the essential principle of the Averroistic theory, and is in harmony with the cardinal doctrine of Mohammedanism—­the unity of God.