Library Theodoret Compendium of Heretical Fables
Book 1
On Secundus and others
Secundus, succeeding Valentinus, divided the Ogdoad in two, and called one part of it Right and the other Left; and he added Light and Darkness. And countless other leaders of heresy sprang up from here—Cossianus, Theodotus, Heracleon, Ptolemaeus, Marcus—inventing various additional doctrines.
Greek: Theodoret of Cyrus, Haereticarum fabularum compendium / Αἱρετικῆς κακομυθίας ἐπιτομή (CPG 6223; PG 83, 336–556). English: study translation for BWAB Library—not a modern copyrighted translation. The full five books are hosted here.