Definite references do not occur before the 2nd century (Fronto, Ep. ad ~k~. Caes. i. 3; Aulus Gellius, Noct. Att. i~. 24, Xii. 10, XjX. 9 Apuleius, De magic, 30; Porphyrion, Ad Horat. carm. iii. 1, 2).