Plutarch, De Iside et Osiride 37

ἔτι τε τὸν κιττὸν Ἕλληνές τε καθιεροῦσι τῷ Διονύσῳ καὶ παρʼ Αἰγυπτίοις λέγεται χενόσιρις ὀνομάζεσθαι, σημαίνοντος τοῦ ὀνόματος, ὥς φασι, φυτὸν Ὀσίριδος. ἀρίστων τοίνυν ὁ γεγραφὼς Ἀθηναίων ἀποικίας ἐπιστολῇ τινι Ἀλεξάρχου περιέπεσεν, ἐν Διὸς ἱστορεῖται καὶ Ἴσιδος υἱὸς ὢν ὁ Διόνυσος ὑπʼ Αἰγυπτίων οὐκ Ὄσιρις ἀλλʼ Ἀρσαφὴς ἐν τῷ ἄλφα γράμματι λέγεσθαι, δηλοῦντος τὸ ἀνδρεῖον τοῦ ὀνόματος. ἐμφαίνει δὲ τοῦτο καὶ ὁ Ἑρμαῖος ἐν τῇ πρώτῃ περὶ τῶν Αἰγυπτίων· ὄμβριμον γάρ φησι μεθερμηνευόμενον εἶναι τὸν Ὄσιριν. ἐῶ δὲ Μνασέαν τῷ Ἐπάφῳ προστιθέντα τὸν Διόνυσον καὶ τὸν Ὄσιριν καὶ τὸν Σάραπιν· ἐῶ καὶ Ἀντικλείδην λέγοντα τὴν Ἶσιν Προμηθέως οὖσαν θυγατέρα Διονύσῳ συνοικεῖν· αἱ γὰρ εἰρημέναι περὶ τὰς ἑορτὰς καὶ τὰς θυσίας οἰκειότητες ἐναργεστέραν τῶν μαρτύρων τὴν πίστιν ἔχουσι.

Moreover, the Greeks are wont to consecrate the ivy to Dionysus, and it is said that among the Egyptians the name for ivy is chenosiris, the meaning of the name being, as they say, the plant of Osiris. Now, Ariston, the author of Athenian Colonization, happened upon a letter of Alexarchus, in which it is recorded that Dionysus was the son of Zeus and Isis, and is called not Osiris, but Arsaphes, spelled with an a, the name denoting virility. Hermaeus, too, makes this statement in the first volume of his book The Egyptians; for he says that Osiris, properly interpreted, means sturdy. I leave out of account Mnaseas’s annexation of Dionysus, Osiris, andSerapis to Epaphus, as well as Anticleides’ statement that Isis was the daughter of Prometheus and was wedded to Dionysus. The fact is that the peculiarities already mentioned regarding the festival and sacrifices carry a conviction more manifest than any testimony of authorities.