The Republic by Plato Part 6 Page 37

Then were we not right in saying that even the very qualities which make a man a philosopher may, if he be ill-educated, divert him from philosophy, no less than riches and their accompaniments and the other so-called goods of life?

We were quite right.

Thus, my excellent friend, is brought about all that ruin and failure which I have been describing of the natures best adapted to the best of all pursuits; they are natures which we maintain to be rare at any time; this being the class out of which come the men who are the authors of the greatest evil to States and individuals; and also of the greatest good when the tide carries them in that direction; but a small man never was the doer of any great thing either to individuals or to States.

That is most true, he said.