Esoteric (Greek ἐσωτερικός), scientific as opposed to popular; applied, especially with regard to the ancient mysteries, to doctrines taught only to the initiated, as distinguished from exoteric. (ἔξω, without) doctrines, which could be taught to the vulgar and uninitiated. "The philosophy of the Pythagoreans, like that of the other sects, was divided into the cxoteric and the esoteric; the open, taught to all; and the secret, taught to a select number" (Warburton, Div. Leg. book 2, note B B). "According to Origen, Aulus Gellius, Porphyry, and Jamblichus, the distinction of esoteric and exoteric among the Pythagoreans was applied to the disciples, according to the de.ree of initiation to which they had attained, being fully admitted into the society, or being merely postulants (Ritter, Hist. Plilos., French transl., 1:248). Plato is said to have had doctrines which he taught publicly to all, and other doctrines which he taught only to a few, in secret. There is no allusion to such a distinction of doctrines in the writings of Plato. Aristotle (Physica, 4:2) speaks of opinions of Plato which were not written. But it does not follow that these were secret. Aristotle himself frequently speaks of some of his writings as exoteric, and others as acroamatic or esoteric. The former treat of the same subjects as the latter, but in a popular and elementary way, while the esoteric are more scientific in their form and matter (Ravaisson, Essai sur la Metaph. d'Aristote, t. 1, c. 1; Tucker, Light of Nature, volume 2, chapter 2)." — Fleming, Vocabulary of Philosophy, s.v.