On the difference between Oriental emanation and eternal generation, see Shedd, Dogm. Theol., 1:470, and History Doctrine, 1:11-18, 318, note—“1. That which is eternally generated is infinite, not finite; it is a divine and eternal person who is not the world or any portion of it. In the Oriental schemes, emanation is a mode of accounting for the origin of the finite. But eternal generation still leaves the finite to be originated. The begetting of the Son is the generation of an infinite person who afterwards creates the finite universe _de nihilo_. 2. Eternal generation has for its result a subsistence or personal hypostasis totally distinct from the world; but emanation In relation to the deity yields only an impersonal or at most a personified energy or effluence which is one of the powers or principles of nature—a mere _anima mundi_.” The truths of which emanation was the perversion and caricature were therefore the generation of the Son and the procession of the Spirit.
Principal Tulloch, in Encyc. Brit., 10:704—“All the Gnostics agree in regarding this world as not proceeding immediately from the Supreme Being.... The Supreme Being is regarded as wholly inconceivable and indescribable—as the unfathomable Abyss (Valentinus)—the Unnameable (Basilides). From this transcendent source existence springs by emanation in a series of spiritual powers.... The passage from the higher spiritual world to the lower material one is, on the one hand, apprehended as a mere continued degeneracy from the Source of Life, at length terminating in the kingdom of darkness and death—the bordering chaos surrounding the kingdom of light. On the other hand the passage is apprehended in a more precisely dualistic form, as a positive invasion of the kingdom of light by a self-existent kingdom of darkness. According as Gnosticism adopted one or other of these modes of explaining the existence of the present world, it fell into the two great divisions which, from their places of origin, have received the respective names of the Alexandrian and Syrian Gnosis. The one, as we have seen, presents more a Western, the other more an Eastern type of speculation. The dualistic element in the one case scarcely appears beneath the pantheistic, and bears resemblance to the Platonic notion of the ὕλη, a mere blank necessity, a limitless void. In the other case, the dualistic element is clear and prominent, corresponding to the Zarathustrian doctrine of an active principle of evil as well as of good—of a kingdom of Ahriman, as well as a kingdom of Ormuzd. In the Syrian Gnosis ... there appears from the first a hostile principle of evil in collision with the good.”