3. A third duty of the physician is to use only safe means in medical and surgical practice. He has no right to expose his patient to needless danger. What is to be thought of the use of such remedies as will either kill or cure? They cannot be used as long as safer remedies are available and capable of effecting a cure; for neither Doctor nor patient has a right to expose a human life to unnecessary risk. But when no safer remedies are going to effect a cure, then prudence itself dictates the employment of the only means to success. In such a case, however, the patient, or his parents or guardian, should, as a rule, be informed of the impending danger, so that they may give or refuse their consent if they please. For, next to God, the right to that life belongs to them rather than to the physician. The same duty of consulting their wishes exists when not life but the possible loss of a limb is at stake, or the bearing of uncommon sufferings. Moralists teach that a man is not obliged in conscience to submit to an extraordinarily painful or revolting operation even to save his life. Certainly, when the natural law leaves him at liberty, the physician cannot compel him to submit to his dictation; all he can do is to obtain his consent by moral persuasion. 4. As a consequence from the Doctor's duty to use only safe means it follows that he cannot experiment on his patients by the use of treatment of which he does not know the full power for good or evil. Nor is he excused from responsibility in this matter by the fact that the experiment thus made on one patient may be very useful to many others. His contract is with the one now under treatment, who is not willing, as a rule to be experimented upon for the benefit of others. And even if the patient should be willing, the Doctor cannot lawfully expose him to grievous danger unless it be the only hope of preserving his life. This follows from the principle explained before, that human life belongs chiefly to God and not to man exclusively.