Diogenes Laertius 7.1.2 (on Zeno, tr. R.D. Hicks):
It is stated by Hecato and by Apollonius of Tyre in his first book on Zeno that he consulted the oracle to know what he should do to attain the best life, and that the god's response was that he should take on the complexion of the dead. Whereupon, perceiving what this meant, he studied ancient authors.
Ἑκάτων δέ φησι καὶ Ἀπολλώνιος ὁ Τύριος ἐν πρώτῳ Περὶ Ζήνωνος, χρηστηριασαμένου αὐτοῦ τί πράττων ἄριστα βιώσεται, ἀποκρίνασθαι τὸν θέον, εἰ συγχρωτίζοιτο τοῖς νεκροῖς· ὅθεν ξυνέντα τὰ τῶν ἀρχαίων ἀναγινώσκειν.