kernel. For man is naturally fond of two things, namely, freedom from control and some pleasure in his activity; for which reason no one without reason submits himself to the control of others, or willingly engages in any tedious task. For pleasure crowns activity, as beauty is a crown to youth, as Aristotle truly asserts in the tenth book of the Ethics. Accordingly the wisdom of the ancients devised a remedy by which to entice the wanton minds of men by a kind of pious fraud, the delicate Minerva secretly lurking beneath the mask of pleasure. We are wont to allure children by rewards, that they may cheerfully learn what we force them to study even though they are unwilling. For our fallen nature does not tend to virtue with the same enthusiasm with which it rushes into vice. Horace has expressed this for us in a brief verse of the Ars Poetica, where he says:
All poets sing to profit or delight.
And he has plainly intimated the same thing in another verse of the same book, where he says:
He hits the mark, who mingles joy with use.
How many students of Euclid have been repelled
