  Proclus, however, also applies this principle to explain the most difficult problem facing Neoplatonic metaphysics, namely, how to understand the procession of the manifold from the One. How can the One be wholly without multiplicity, when it must somehow be the cause of any and all multiplicity? The One remains in itself absolutely unparticipated; the many different beings proceeding from it participate in a series of participated henads or unities (gods). According to some scholars it was Iamblichus who introduced this innovative doctrine, others attribute it to Proclus’ teacher Syrianus. Even if the doctrine does not originate as such from Iamblichus himself, the existence of the divine henads somehow follows from his law of mean terms. This law states that “every producing cause brings into existence things like to itself before the unlike.“ (Elem. Theol. § 28).  Thus there are no leaps in the chain of being, but everything is linked together by similar terms. The henads fulfill this function, for as participated unities they bridge the gap between the transcendent One and everything that comes after it. The doctrine of the henads can thus be seen as a way of integrating the traditional gods of Greek polytheistic religion into the Neoplatonic metaphysics of the One.