XXV. The reading of good books is very useful, to instruct Princes in the maxims of sound policy. But which are the good books? I believe very few. Those which contain sound doctrine are infinite; but what signifies their informing, if they don’t stimulate or move? The most difficult part of morality, does not so much consist in coming at a knowledge of what is right, as in exciting and moving an effectual inclination to practise it. There are books of short sentences, and abounding with affectation, (in the stile of Seneca, which a certain Emperor called sand without lime) which tingle in the ear, but their echo never reaches the heart. There are others, filled with texts and pulpit conceits, which, instead of illustrating, confound, and instead of moving, become tiresome and surfeiting. There are others again, which abound with the sentences of Thucydides, Polybius, Tacitus, Livy, and Sallust, intermixed with a number of historical passages. I shall say of all these, as Apelles said of a pupil of his, who had painted Helen with very little beauty, but in a very costly dress stuck full of jewels: _Cum non posses facere pulchram, fecisti divitem. As you was unable to make her handsome, you have made her rich._ These forced and unnatural ornaments, with which erudition in the books that treat of it, dress virtue, do not conduce to fire the minds of those who read them, with the love of her. He only will accomplish this end, who has the art of painting in lively colours her native beauty; and who has the address and genius, to impress on the understanding, a clear and agreeable idea, of the magnificence of her charms.