Some, however, think the rule should be, “let a friend be content with his stated wage.” 232

But if a man, after being paid in advance, fulfils none of his engagements, because he had promised more than he could perform, he is rightly held chargeable; for he does not fulfil his contract. But the sophists, perhaps, are compelled to adopt this plan [of payment in advance]; for otherwise no one would give anything for what they know.