I cannot find this me in Smyth: ‘οὔτοι ἀπόβλητον ἔπος’ εἶναι δεῖ, ὦ Φαῖδρε, ὃ ἂν εἴπωσι σοφοί, ἀλλὰ σκοπεῖν μή τι λέγωσι: καὶ δὴ καὶ τὸ νῦν λεχθὲν οὐκ ἀφετέον. (Phdr., 260a) The subj. is probably potential.
Hi, this is actually a typical classical construction (nothing Plato-specific here). The subj. is not potential.
You have σκοπεῖν (a ‘verb of effort’) in an ‘apprehension’ construction with a ‘fear’ object clause (μή w. subj.). See Smyth 2224a for the construction:
a. Sometimes it is not actual fear that is expressed but only apprehension, anxiety, suspicion, etc. These are the verbs and expressions of caution: ὀκνῶ, ἀθυμῶ, ἀπιστῶ, ἀπιστίαν ἔχω (παρέχω), ὑποπτεύω, ἐνθυμοῦμαι, αἰσχύνομαι (rare), κίνδυνός ἐστι, προσδοκία ἐστί. Here belong also, by analogy, ὁρῶ, > σκοπῶ> , ἐννοῶ, εὐλαβοῦμαι, φροντίζω, φυλάττω (-ομαι), which admit also the construction of verbs of effort (2210 b).
Then see 2221 and ff. for the negative μή.
The Cambridge grammar has some useful coverage of this too, e.g. at 44.6:
Not infrequently, > verbs of effort are construed with fear clauses > (with μή + subjunctive/optative)…
They then give this e.g. from Aristophanes’ Thesmophoriazusae re. apprehension for a present state:
ὑποβλέπουσ᾽ ἡμᾶς > σκοποῦνταί > τ᾽ εὐθέως
μὴ > μοιχὸς ἔνδον > ᾖ > τις ἀποκεκρυμμένος.
I’d also recommend using a commentary if you are doing a close reading. This construction is covered in e.g. Ryan’s commentary on the Phaedrus (2012 p. 249):
An element of apprehension is present in σκοπεῖν, enabling it to govern the kind of subordinate clause that is normal with verbs of fearing (S. 2224a with 2225)… the subjunctive transmitted by the tradition and printed by Burnet here yields perfectly good sense: ‘pay heed lest they turn out to be saying something important’; they are saying these things now and have said them in the past, but we may, to our embarrassment, discover in the future that we ought to have paid attention.
Cheers, Chad