Probably actual cases of the instinct of natural death in man are as rare as instances of the secretion of milk by males. But favouring circumstances and some education of the instinct of death would probably reawaken it and develop it fully. There is much work to be done before so great an object can be achieved. But it is the peculiar feature of science to be eager for much labour, while religions and systems of metaphysical philosophy are content with passive fatalism and silent resignation. The mere hope of being able to solve the great problems of humanity in the more or less distant future brings much satisfaction. When Tolstoi, agonised by the impossibility of solving the great problems, and haunted by the fear of death, asked if the love of our children is not able to sooth our souls, he found that such a hope was vain. “What is the good,” he said, “of rearing children who will soon find themselves in the same difficult position as their parents?” “Why should they live? why should I love them and protect them and foster them? Is it that they may come to the same despair as I am in myself or else grow imbecile? As I love them, I do not wish to hide the truth from them, for each step in knowledge will lead them nearer to it. But the truth is—death.” I can understand that many persons would abstain from having children if they had come to these pessimistic conclusions. The point of view that I have exposed in this book will make life more possible. Our generation has no chance of attaining physiological old age and normal death; but it may take real consolation from the thought that those who are now young may advance several steps in that direction. It may reflect that each succeeding generation will get closer and closer to the solution and that true happiness one day will be reached by mankind. The slow advance to happiness will demand many sacrifices. Already, men of science sacrifice their health and sometimes their life to reach the solution of some important problem, as for instance, to clear up a medical question, and so be ready to heal or to save the lives of their fellows. Before it is possible to reach the goal, mankind must be persuaded that science is all-powerful and that the deeply rooted existing superstitions are pernicious. It will be necessary to reform many customs and many institutions that now seem to rest on enduring foundations. The abandonment of much that is habitual and a revolution in the mode of education will require long and painful effort.