[313a] καὶ ἐγὼ εἶπον μετὰ τοῦτο· τί οὖν; οἶσθα εἰς οἷόν τινα κίνδυνον ἔρχῃ ὑποθήσων τὴν ψυχήν; ἢ εἰ μὲν τὸ σῶμα ἐπιτρέπειν σε ἔδει τῳ διακινδυνεύοντα ἢ χρηστὸν αὐτὸ γενέσθαι ἢ πονηρόν, πολλὰ ἂν περιεσκέψω εἴτ’ ἐπιτρεπτέον εἴτε οὔ, καὶ εἰς συμβουλὴν τούς τε φίλους ἂν παρεκάλεις καὶ τοὺς οἰκείους σκοπούμενος ἡμέρας συχνάς· ὃ δὲ περὶ πλείονος τοῦ σώματος ἡγῇ, τὴν ψυχήν, καὶ ἐν ᾧ πάντ’ ἐστὶν τὰ σὰ ἢ εὖ ἢ κακῶς πράττειν, χρηστοῦ ἢ πονηροῦ αὐτοῦ γενομένου, περὶ δὲ τούτου οὔτε τῷ πατρὶ οὔτε τῷ ἀδελφῷ [313b] ἐπεκοινώσω οὔτε ἡμῶν τῶν ἑταίρων οὐδενί, εἴτ’ ἐπιτρεπτέον εἴτε καὶ οὐ τῷ ἀφικομένῳ τούτῳ ξένῳ τὴν σὴν ψυχήν, ἀλλ’ ἑσπέρας ἀκούσας, ὡς φῄς, ὄρθριος ἥκων περὶ μὲν τούτου οὐδένα λόγον οὐδὲ συμβουλὴν ποιῇ, εἴτε χρὴ ἐπιτρέπειν σαυτὸν αὐτῷ εἴτε μή, ἕτοιμος δ’ εἶ ἀναλίσκειν τά τε σαυτοῦ καὶ τὰ τῶν φίλων χρήματα, ὡς ἤδη διεγνωκὼς ὅτι πάντως συνεστέον Πρωταγόρᾳ, ὃν οὔτε γιγνώσκεις, ὡς φῄς, οὔτε [313c] διείλεξαι οὐδεπώποτε, σοφιστὴν δ’ ὀνομάζεις, τὸν δὲ σοφιστὴν ὅτι ποτ’ ἔστιν φαίνῃ ἀγνοῶν, ᾧ μέλλεις σαυτὸν ἐπιτρέπειν;
καὶ ὃς ἀκούσας, ἔοικεν, ἔφη, ὦ Σώκρατες, ἐξ ὧν σὺ λέγεις.
ἆρ’ οὖν, ὦ Ἱππόκρατες, ὁ σοφιστὴς τυγχάνει ὢν ἔμπορός τις ἢ κάπηλος τῶν ἀγωγίμων, ἀφ’ ὧν ψυχὴ τρέφεται; φαίνεται γὰρ ἔμοιγε τοιοῦτός τις.
τρέφεται δέ, ὦ Σώκρατες, ψυχὴ τίνι;
μαθήμασιν δήπου, ἦν δ’ ἐγώ. καὶ ὅπως γε μή, ὦ ἑταῖρε, ὁ σοφιστὴς ἐπαινῶν ἃ πωλεῖ ἐξαπατήσῃ ἡμᾶς, ὥσπερ οἱ περὶ τὴν τοῦ σώματος τροφήν, ὁ [313d] ἔμπορός τε καὶ κάπηλος. καὶ γὰρ οὗτοί που ὧν ἄγουσιν ἀγωγίμων οὔτε αὐτοὶ ἴσασιν ὅτι χρηστὸν ἢ πονηρὸν περὶ τὸ σῶμα, ἐπαινοῦσιν δὲ πάντα πωλοῦντες, οὔτε οἱ ὠνούμενοι παρ’ αὐτῶν, ἐὰν μή τις τύχῃ γυμναστικὸς ἢ ἰατρὸς ὤν. οὕτω δὲ καὶ οἱ τὰ μαθήματα περιάγοντες κατὰ τὰς πόλεις καὶ πωλοῦντες καὶ καπηλεύοντες τῷ ἀεὶ ἐπιθυμοῦντι ἐπαινοῦσιν μὲν πάντα ἃ πωλοῦσιν, τάχα δ’ ἄν τινες, ὦ ἄριστε, καὶ τούτων ἀγνοοῖεν ὧν πωλοῦσιν ὅτι χρηστὸν ἢ πονηρὸν [313e] πρὸς τὴν ψυχήν· ὡς δ’ αὕτως καὶ οἱ ὠνούμενοι παρ’ αὐτῶν, ἐὰν μή τις τύχῃ περὶ τὴν ψυχὴν αὖ ἰατρικὸς ὤν. εἰ μὲν οὖν σὺ τυγχάνεις ἐπιστήμων τούτων τί χρηστὸν καὶ πονηρόν, ἀσφαλές σοι ὠνεῖσθαι μαθήματα καὶ παρὰ Πρωταγόρου καὶ παρ’ ἄλλου ὁτουοῦν·
from Burnet's (1903) Oxford Classical Text, courtesy of the Perseus Project
An original translation
Here I said, “What? Do you know the sort of risk you’re running by gambling your soul? Look, if you had to hand over your body to someone and run the risk for better or worse, you’d look long and hard into whether you should do it or not. You’d call your friends and family together for advice for days on end to ﬁgure it out. But as for what you rate higher than your body – your soul – on which your success or failure entirely depends, as it turns to better or worse – about this, do you bother to consult your father or your brother or a single one of your friends about whether you should hand over your soul or not to this stranger who just turned up? No, as you say, you only found out last night and you’ve come this morning, without hearing argument or advice about it, ready to spend your own money and your friends’ money, since you’ve already ﬁgured out that you absolutely have to spend time with Protagoras, whom you don’t know and haven’t ever spoken to, as you admit. And you call the person you’re about to hand over your soul to a sophist, but you clearly don’t know what that is.”
When he heard this, he replied, “Well, it seems to be as you say, Socrates.”
“So, Hippocrates, maybe the sophist is a kind of shopkeeper or a retailer of stuﬀ which keeps the soul fed? Because that’s the kind of person he seems to me.”
“But what does the soul feed on, Socrates?”
“On lessons, I suppose. But watch out, so the sophist won’t deceive us when he praises what he sells, just like a shopkeeper or a peddler who sells food for the body might. In fact, these people don’t even know themselves which of their products is better or worse for the body, but they praise everything they sell. And their customers don’t know either, unless they happen to be a ﬁtness or medical expert. The same goes for those who go city to city, selling and hawking their lessons to anyone who’s interested. While they praise everything they sell, my friend, some of them probably don’t know whether their stuff is good or bad for the soul. Their customers are also ignorant unless, again, they happen to be doctors for the soul. So, if you somehow know which of their lessons is good or bad for you, it’s safe for you to buy from Protagoras or anyone else.
Jowett's translation (1871)
Then I proceeded to say: Well, but are you aware of the danger which you are incurring? If you were going to commit your body to some one, who might do good or harm to it, would you not carefully consider and ask the opinion of your friends and kindred, and deliberate many days as to whether you should give him the care of your body? But when the soul is in question, which you hold to be of far more value than the body, and upon the good or evil of which depends the well-being of your all,-about this never consulted either with your father or with your brother or with any one of us who are your companions. But no sooner does this foreigner appear, than you instantly commit your soul to his keeping. In the evening, as you say, you hear of him, and in the morning you go to him, never deliberating or taking the opinion of any one as to whether you ought to intrust yourself to him or not;-you have quite made up your mind that you will at all hazards be a pupil of Protagoras, and are prepared to expend all the property of yourself and of your friends in carrying out at any price this determination, although, as you admit, you do not know him, and have never spoken with him: and you call him a Sophist, but are manifestly ignorant of what a Sophist is; and yet you are going to commit yourself to his keeping.
When he heard me say this, he replied: No other inference, Socrates, can be drawn from your words.
I proceeded: Is not a Sophist, Hippocrates, one who deals wholesale or retail in the food of the soul? To me that appears to be his nature.
And what, Socrates, is the food of the soul?
Surely, I said, knowledge is the food of the soul; and we must take care, my friend, that the Sophist does not deceive us when he praises what he sells, like the dealers wholesale or retail who sell the food of the body; for they praise indiscriminately all their goods, without knowing what are really beneficial or hurtful: neither do their customers know, with the exception of any trainer or physician who may happen to buy of them. In like manner those who carry about the wares of knowledge, and make the round of the cities, and sell or retail them to any customer who is in want of them, praise them all alike; though I should not wonder, O my friend, if many of them were really ignorant of their effect upon the soul; and their customers equally ignorant, unless he who buys of them happens to be a physician of the soul. If, therefore, you have understanding of what is good and evil, you may safely buy knowledge of Protagoras or of any one.
Compare Lamb's (1924) translation at the Perseus Project