Valentinius, a mid-2nd century Gnostic thinker and preacher, was among the early Christians who attempted to align Christianity with middle Platonism. Valentinius pooled dual concepts from the Platonic world of ideal forms, or fullness (pleroma), and the lower world of phenomena, or emptiness (kenoma, κένωμα). Employing a third concept of cosmos, what is manifest, Valentinian initiates could exegete scripture in light of these three aspects of correlated existence.
The pleroma is the abode of the Æons . . . they are, or they comprise, the eternal ideas or archetypes of the Platonic philosophy. . . . Separated from this celestial region by Horus . . . or Boundary . . . lies the ‘kenoma’ or ‘void’—the kingdom of this world, the region of matter and material things, the land of shadow and darkness. Here is the empire of the Demiurge or Creator, who is not a celestial Æon at all, but was born in this very void over which he reigns. Here reside all those phenomenal, deceptive, transitory things, of which the eternal counterparts are found only in the pleroma. . . . All things are set off one against another in these two regions: just as
The ancient Greek term for emptiness or void (kenoma), as pertaining to Theodotus's exegesis of Gospel of John chapter 1 verse 3, is described in The Excerpta ex Theodoto of Clement of Alexandria (Casey, 1934).
Elsewhere, the usual antithesis to Pleroma is not Kenoma, but Hysterema (ὑστέρημα). As the system is reported by Hippolytus (vi. 31, p. 180) this word is used as the complement of the word Pleroma, denoting all that is not included in the meaning of the latter word. Thus the Horos or boundary is described as separating the Hysterema from the Pleroma, itself partaking of the nature of both; but preserving all inside fixed and immovable by permitting nothing from without to enter. We can understand in the same sense the passage in Epiphanius (Haer. 31, 4, p. 166), where the same name is given to the Demiurge; for it appears in the case of the word Hebdomas that the Valentinians gave to the Demiurge the name of the realm over which he ruled, and from which he had his origin.