Passage 5.18.4
πεποίηνται δὲ καὶ ᾄδουσαι Μοῦσαι καὶ Ἀπόλλων ἐξάρχων τῆς ᾠδῆς, καί σφισιν ἐπίγραμμα γέγραπται· Λατοΐδας οὗτος τάχʼ ἄναξ ἑκάεργος Ἀπόλλων· Μοῦσαι δʼ ἀμφʼ αὐτόν, χαρίεις χορός, αἷσι κατάρχει. Ἄτλας δὲ ἐπὶ μὲν τῶν ὤμων κατὰ τὰ λεγόμενα οὐρανόν τε ἀνέχει καὶ γῆν, φέρει δὲ καὶ τὰ Ἑσπερίδων μῆλα. ὅστις δέ ἐστιν ὁ ἀνὴρ ὁ ἔχων τὸ ξίφος καὶ ὁ ἐπὶ τὸν Ἄτλαντα ἐρχόμενος, ἰδίᾳ μὲν ἐπʼ αὐτῷ γεγραμμένον ἐστὶν οὐδέν, δῆλα δὲ ἐς ἅπαντας Ἡρακλέα εἶναι. γέγραπται δὲ καὶ ἐπὶ τούτοις· Ἄτλας οὐρανὸν οὗτος ἔχει, τὰ δὲ μᾶλα μεθήσει.
Also represented are the Muses singing, with Apollo leading the song, and inscribed for them is the following epigram: "This is Leto's son, the far-shooting lord Apollo; around him are the Muses, a lovely chorus, whom he leads in song." Atlas, it is said, supports heaven and earth upon his shoulders, and he also holds the apples of the Hesperides. As for the man holding a sword and approaching Atlas, there is no inscription to identify him specifically, but it is clear to everyone that he is Herakles. There is also another inscription with these figures: "This Atlas holds up the sky, but soon he will surrender the apples."