Secundians a Gnostic sect of the 2d century, owning for their leader Secundus, "who was born," says Hippolytus, "about the same time as Ptolemaeus," and thus was contemporary with the immediate followers of Valentinus. Irenaeus represents the Secundians as a branch of the Valentinian school (Hoeres. 1, 11, 2); but, although they emanated from that school (Hippolytus, Refut. 6, 32, 33), they introduced a principle so distinct as to render Secundus more properly a rival than the disciple of Valentinus. Secundus placed at the head of his AEons, whom he appears to have considered as real substances or persons, two principles, Light and Darkness. "He divides the Ogdoad into a pair of Tetrads, a right hand and a left Tetrad, one Light and the other Darkness" (Tertullian Adv. Valent. 38). This admission of the principle of dualism constitutes an essential difference between the Secundians and the Valentinians. It is evidently borrowed from the Oriental philosophy, and brings the Secundians so far nearer the Manichaeans. Accordingly, Dorner classes as adherents of the dualism whose character was predominantly physical, the Ophites, Saturnilus, Secundus, and subsequently the Manichaeans; as adherents of pantheistic Monism; Valentinus and his widespread school, especially Heracleon his contemporary, Ptolemaeus, and Marcus (Person of Christ, 1, append. p. 448). There is also mentioned as a distinction between the Valentinians and Secundus that the latter did not derive the power Acharnoth from any one of the thirty AEons, but from the fruits which issued out of their substance (Tertullian, ut sup.). He invented first four more AEons, and then four in addition (Pseudo-Tertullian, 13). The Secundians were Docetae. Augustine (Hoeres. 12) and Auctor Praedestinati (12) charge them with gross immorality. The latter adds that they were condemned by Diodorus, bishop of Crete.