καὶ ἀδύνατος ὤν: in form coordinate with, but in sense explanatory of, οὕτως διακείμενος, which refers to what precedes.
εἰ ἐκεῖνό γε κτἑ.: the apod. is to be sought in the implied affirmation to the question δοκεῖ σοι καλῶς ἔχειν. Cf. 503 c. The addition of ἕν to the pron. makes it very emphatic, as in Rep. vii. 537 b (though here the order is different) μία καὶ αὕτη τῶν βασάνων οὐκ ἐλαχίστη.
βεβοηθηκὼς εἴη: not to be considered as a circumlocutory perfect; but the partic. denotes a condition brought about by a course of action (εἰρηκὼς μήτε εἰργασμένος) which, begun in the past, still continues.
