ἀλλὰ δεῖ ἐκ τῶν ποιητῶν ἀναμιμνῄσκεσθαι ὅτι πολλαχοῦ λέγουσιν περὶ ὅτου ἂν τύχωσιν τῶν ἀρχομένων ταχὺ προϊέναι ‘ἐσύθη’ φασίν.
This φασίν is redundant, is it common in Plato?
It’s not redundant.
“Often when poets talk (λέγουσιν) about X they say / use the word (φασίν) Y.”
but there is no ‘when’ in the text, so it is rather: but we must remember that the poets often speak about whatever begins to advance, they say ἐσύθη (it rushed).