Many ways of preventing conception have been devised since the method which is still the commonest was first introduced, so far as our certainly imperfect knowledge extends, by a clever Jew, Onan (_Genesis_, Chap. XXXVIII), whose name has since been wrongly attached to another practice with which the Mosaic record in no way associates him. There are now many contraceptive methods, some dependent on precautions adopted by the man, others dependent on the woman, others again which take the form of an operation permanently preventing conception, and, therefore, not to be adopted save by couples who already have as many children as they desire, or else who ought never to have children at all and thus wisely adopt a method of sterilisation. It is unnecessary here, even if it were otherwise desirable, to discuss these various methods in detail. It is even useless to do so, for we must bear in mind that no method can be absolutely approved or absolutely condemned. Each may be suitable under certain conditions and for certain couples, and it is not easy to recommend any method indiscriminately. We need to know the intimate circumstances of individual cases. For the most part, experience is the final test. Forel compared the use of contraceptive devices to the use of eyeglasses, and it is obvious that, without expert advice, the results in either case may sometimes be mischievous or at all events ineffective. Personal advice and instruction are always desirable. In Holland nurses are medically trained in a practical knowledge of contraceptive methods, and are thus enabled to enlighten the women of the community. This is an admirable plan. Considering that the use of contraceptive measures is now almost universal, it is astonishing that there are yet so many so-called "civilised" countries in which this method of enlightenment is not everywhere adopted. Until it is adopted, and a necessary knowledge of the most fundamental facts of the sexual life brought into every home, the physician must be regarded as the proper adviser. It is true that until recently he was generally in these matters a blind leader of the blind. Nowadays it is beginning to be recognised that the physician has no more serious and responsible duty than that of giving help in the difficult path of the sexual life. Very frequently, indeed, even yet, he has not risen to a sense of his responsibilities in this matter. It is as well to remember, however, that a physician who is unable or unwilling to give frank and sound advice in this most important department of life, is unlikely to be reliable in any other department. If he is not up to date here he is probably not up to date anywhere.