_I have proposed to myself to write on the diseases produced by self-pollution, and not on the crime of self-pollution, considered as a crime; is it not proof enough of its being one, the demonstrating that it is an act of self-murther? Whoever knows mankind, will not be difficultly persuaded, that it is easier to give them an aversion against a vice, by the fear of a present evil, than by reasons founded on principles, of which there is not care enough taken to inculcate to them all the truth and solidity. I have applied to myself what an author, whose name will pass to the remotest posterity, as an honor to the age in which he lived, makes a Clergyman say: “We are put upon undertaking to prove the utility of prayer, to a man who does not believe there is a God; and the necessity of fasting, to one who has, all his life, denied the immortality of the soul: such an attempt is rather difficult, and the laugh is not on our side[1].” MARPHURIUS doubted of every thing till SGANARELLE broke his bones; and then MARPHURIUS believed._ _These ZOÏLUSES of society and literature, who themselves do nothing, and blame every thing that is done, will have the assurance to say, that this Work is fitter to spread than to stop this vice, and that it will make it known to such as would otherwise have remained in ignorance of it. I shall make them no answer; they deserve none; it is debasing one’s self to do them that honor: but there are those of weak though virtuous minds, upon whom these objections might make an impression: to these I owe a general reflexion, it is this, that, in that point of light, my Book is liable to no worse exception than what might be made to all books of morality: they must be all prohibited, if pointing out the dangers of a vice was the way to multiply it. The sacred writings, those of the Fathers, those of the Casuists, ought all to be forbidden before mine is so. Besides, what young person is likely to think of reading a Treatise of Physic on a matter of which he does not so much as know the name? It is to be wished, indeed, that this Book were become familiar to all persons to whom the education of youth is committed; it might be of service to them to set an early watch; and detect, in time, any practice of this detestable habit; it would enable them to take the precautions they should judge necessary for preventing the consequences._