The following is an excerpt from Plato’s Republic.
Why, that all those mercenary individuals, whom the many call Sophists and whom they deem to be their adversaries, do, in fact, teach nothing but the opinion of the many, that is to say, the opinions of their assemblies; and this is their wisdom. I might compare them to a man who should study the tempers and desires of a mighty strong beast who is fed by him—he would learn how to approach and handle him, also at what times and from what causes he is dangerous or the reverse, and what is the meaning of his several cries, and by what sounds, when another utters them, he is soothed or infuriated; and you may suppose further, that when, by continually attending upon him, he has become perfect in all this, he calls his knowledge wisdom, and makes of it a system or art, which he proceeds to teach, although he has no real notion of what he means by the principles or passions of which he is speaking, but calls this honourable and that dishonourable, or good or evil, or just or unjust, all in accordance with the tastes and tempers of the great brute. Good he pronounces to be that in which the beast delights and evil to be that which he dislikes; and he can give no other account of them except that the just and noble are the necessary, having never himself seen, and having no power of explaining to others the nature of either, or the difference between them, which is immense. By heaven, would not such an one be a rare educator?