5. There are various kinds of medical treatment to which we can scarcely have recourse without exposing ourselves to serious evil consequences. Such is the use of cocaine, morphine, and even in special cases of alcohol. The drugs in themselves are useful, but they often lead to evil results. Now in the use of all such drugs as are apt to be beneficial in one way and injurious in another, we must ever be guided by the rules formerly explained concerning evil indirectly willed, or rather permitted to result, while good results are directly willed or intended. If the Doctor is satisfied that a dose of morphine or an application of cocaine will do more good than harm, he can, of course, prescribe or apply it. Still in such matters he must remember that the good effect is but temporary, while its pernicious consequences, especially when habits are thus contracted, are likely to be permanent and cumulative. Besides, the good results affect the body only, the evil often affect body and soul. Many a wreck in health and morals has been caused by imprudent recourse to dangerous treatment, where a little more patience and wisdom would have been equally efficient in curing the bodily ailment, without any deleterious consequences. If once a patient becomes a slave to the morphine or cocaine habit, the only cure is to cut off all the supply of the drug either at once or, at any rate, by daily diminution. To leave him free control of the poison is to co-operate in his self-destruction. 6. The sixth duty of a Doctor is of a different kind. There exists a tacit or implicit contract between him and his patients that he shall keep their secrets of which he becomes possessed in his professional capacity. It is always wrong wantonly to betray the secrets of others; but the Doctor is bound by a special duty to keep his professional secrets; and it is doubly wrong and disgraceful in him to make them known. For instance, if he has treated a case of sickness brought on by sinful excesses of any kind, he is forbidden by the natural law to talk about it to such as have no special right to know the facts. Parents and guardians are usually entitled to be informed of their children's and their wards' wrong-doings, that they may take proper measures to prevent further evil. Besides, the Doctor is properly in their service; he is paid by them, and, therefore, his contract is with them rather than with the children. He can, therefore, prudently inform them of what is wrong, but he cannot inform others.