This question is of great importance, both in practical philosophy and in juridical and medical practice, and, as opinions differ very much on the subject, it seems advisable to deal with it here. I start from my own personal opinion, that sympathy is not only one of the noblest and finest functions of the human brain, but also one of the first conditions of the social life of the higher animals. The precepts of Christian charity which the gospels rightly place in the very foreground of morality, were not first discovered by Christ, but they were successfully urged by him and his followers at a time when refined selfishness threatened the Roman civilization with decay. These natural principles of sympathy and altruism had arisen thousands of years before in human society, and are even found among all the higher animals that live a social life. They have their first roots in the sexual reproduction of the lower animals, the sexual love and the care of the young on which the maintenance of the species depends. Hence the modern prophets of pure egoism, Friedrich Nietzsche, Max Stirner, etc., commit a biological error when they would substitute their morality of the strong for universal charity, and when they ridicule sympathy as a weakness of character or an ethical blunder of Christianity. It is just in its insistence on sympathy that the Christian teaching is most valuable, and this part of its system will survive long after its dogmas have sunk into oblivion. However, this lofty duty must not be confined to men, but extended to "our relations," the higher vertebrates, and, in fact, to all animals whose brain-organization seems to point to the possession of sensation and a consciousness of pleasure and pain. Thus, for instance, in the case of the domestic animals which we use daily in our service, and which have an undoubted psychic affinity to ourselves, we must take care to increase their pleasures and mitigate their sufferings. Faithful dogs and noble horses, with which we have lived for years and which we love, are rightly put to death and relieved from pain when they fall hopelessly ill in old age. In the same way we have the right, if not the duty, to put an end to the sufferings of our fellow-men. Some severe and incurable disease makes life unbearable for them, and they ask for redemption from evil. However, medical men hold very different opinions on the matter, as I have found in conversation with them. Many experienced physicians, who practise their profession in a spirit of sympathy and without dogmatic prejudice, have no scruple about cutting short the sufferings of the incurable by a dose of morphia or cyanide of potassium when they desire it; very often this painless end is a blessing both to the invalids and their families. However, other physicians and most jurists are of opinion that this act of sympathy is not right, or is even a crime; that it is the duty of the