that they have no proof for this unity, and that the terms employed in their arguments are vague and equivocal, as we have explained elsewhere. Indeed, it has been demonstrated that no existing thing can possess such unity, and that attributing it to the Originator entails negating Him. This is why they ultimately came to maintain that all existence is one.

Yet the world contains observable multiplicity. If what proceeds from the One is one in every respect, then only one thing can proceed from it. They must therefore deny the multiplicity observable in existence, contrary to what is plainly witnessed. If, however, it contains what they call multiplicity, plurality, composition, and the like, then more than one thing has proceeded from the One. They thus face two alternatives: either affirm the One and deny all subsequent effects—the second, third, fourth, and fifth—or affirm multiplicity in the first effect and, in turn, in the Originator.

To illustrate this: the eighth sphere contains numerous stars, while the ninth sphere above it is bare. Where, then, did this immense multiplicity come from? If they say that an intellect proceeded from Him, then from that intellect another intellect, a soul, and a celestial sphere, and so on down to the tenth intellect, from which everything beneath the lunar sphere then proceeded, this account contains contradictions and nonsense that would not pass muster even with children.

When I first became acquainted with their views, shortly after reaching puberty, my eagerness to seek knowledge and investigate these matters was so intense that I would see Ibn Sīnā in my dreams, debating this point with him