The Republic by Plato Part 6 Page 65

Then the aspirant must not only be tested in those labours and dangers and pleasures which we mentioned before, but there is another kind of probation which we did not mention — he must be exercised also in many kinds of knowledge, to see whether the soul will be able to endure the highest of all, or will faint under them, as in any other studies and exercises.

Yes, he said, you are quite right in testing him. But what do you mean by the highest of all knowledge?

You may remember, I said, that we divided the soul into three parts; and distinguished the several natures of justice, temperance, courage, and wisdom?

Indeed, he said, if I had forgotten, I should not deserve to hear more.

And do you remember the word of