Passage 10.32.13
τοῦ δὲ Ἀσκληπιοῦ περὶ τεσσαράκοντα ἀπέχει σταδίους περίβολος καὶ ἄδυτον ἱερὸν Ἴσιδος, ἁγιώτατον ὁπόσα Ἕλληνες θεῷ τῇ Αἰγυπτίᾳ πεποίηνται· οὔτε γὰρ περιοικεῖν ἐνταῦθα οἱ Τιθορεεῖς νομίζουσιν οὔτε ἔσοδος ἐς τὸ ἄδυτον ἄλλοις γε ἢ ἐκείνοις ἐστὶν οὓς ἂν αὐτὴ προτιμήσασα ἡ Ἶσις καλέσῃ σφᾶς διʼ ἐνυπνίων. τὸ δὲ αὐτὸ καὶ ἐν ταῖς ὑπὲρ Μαιάνδρου πόλεσι θεοὶ ποιοῦσιν οἱ καταχθόνιοι· οὓς γὰρ ἂν ἐς τὰ ἄδυτα ἐσιέναι θελήσωσιν, ἀποστέλλουσιν αὐτοῖς ὀνειράτων ὄψεις.
About forty stadia from the sanctuary of Asclepius is an enclosure and sacred shrine of Isis, the most holy of all temples the Greeks have erected to the Egyptian goddess. For the people of Tithorea consider it improper to live close to it, and entry to the inner sanctuary is permitted only to those whom Isis herself, honoring them especially, summons through dreams. The same phenomenon is seen among the cities beyond the Maeander River in the rituals of their chthonic deities: those whom the gods wish to enter their holy places, they signal by sending visionary dreams.