“ It is not true that the inclination to evil is beyond our control, and that we cannot overcome it until we have acquired the habit of yielding to it. ”
 Jean-Jacques Rousseau, Emile, or On Education (1762). copy citation

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“However this may be, I maintain that if instead of the empty precepts which are prematurely dinned into the ears of children, only to be scoffed at when the time comes when they might prove useful, if instead of this we bide our time, if we prepare the way for a hearing, if we then show him the laws of nature in all their truth, if we show him the sanction of these laws in the physical and moral evils which overtake those who neglect them, if while we speak to him of this great mystery of generation, we join to the idea of the pleasure which the Author of nature has given to this act the idea of the exclusive affection which makes it delightful, the idea of the duties of faithfulness and modesty which surround it, and redouble its charm while fulfilling its purpose; if we paint to him marriage, not only as the sweetest form of society, but also as the most sacred and inviolable of contracts, if we tell him plainly all the reasons which lead men to respect this sacred bond, and to pour hatred and curses upon him who dares to dishonour it; if we give him a true and terrible picture of the horrors of debauch, of its stupid brutality, of the downward road by which a first act of misconduct leads from bad to worse, and at last drags the sinner to his ruin; if, I say, we give him proofs that on a desire for chastity depends health, strength, courage, virtue, love itself, and all that is truly good for man—I maintain that this chastity will be so dear and so desirable in his eyes, that his mind will be ready to receive our teaching as to the way to preserve it; for so long as we are chaste we respect chastity; it is only when we have lost this virtue that we scorn it.
It is not true that the inclination to evil is beyond our control, and that we cannot overcome it until we have acquired the habit of yielding to it. Aurelius Victor says that many men were mad enough to purchase a night with Cleopatra at the price of their life, and this is not incredible in the madness of passion. But let us suppose the maddest of men, the man who has his senses least under control; let him see the preparations for his death, let him realise that he will certainly die in torment a quarter of an hour later; not only would that man, from that time forward, become able to resist temptation, he would even find it easy to do so; the terrible picture with which they are associated will soon distract his attention from these temptations, and when they are continually put aside they will cease to recur.” source