In Valentinianism, Nous is the first male Aeon. Together with his conjugate female Aeon, Aletheia (truth), he emanates from the Propator Bythos ( "Forefather Depths") and his co-eternal Ennoia ( "Thought") or Sigē ( "Silence"); and these four form the primordial Tetrad. Like the other male Aeons he is sometimes regarded as androgynous, including in himself the female Aeon who is paired with him. He is the Only Begotten; and is styled the Father, the Beginning of All, inasmuch as from him are derived immediately or mediately the remaining Aeons who complete the Ogdoad (eight), thence the Decad (ten), and thence the Dodecad (twelve); in all, thirty Aeons constitute the Pleroma.