All subjective happiness due to nerve stimulation is of the nature of mania. In proportion to its intensity is the certainty that it will be followed by its subjective reaction, the "Nuit Blanche," the "dark brown taste," by the experience of "the difference in the morning." The only melancholy drugs can drive away is that which they themselves produce. It is folly to use as a source of pleasure that which lessens activity and vitiates life. There are many other causes which induce depression of mind and disorder of nerve. Where nerve decay is associated with genius and culture, we shall find some phase of the philosophy of Pessimism. In fact, cheerfulness is not primarily a result of right thinking, but rather the expression of sound nerves and normal vegetative processes. Most of the philosophy of despair, the longing to know the meaning of the unattainable, vanishes with active out-of-door life and the consequent flow of good health. Even a dose of quinine may convert to hopefulness when both sermons and arguments fail. For a degree of optimism is a necessary accompaniment of health. It is as natural as animal heat, and is the mental reflex of it. Pessimism arises from depression or irritation or failure of the nerves. It is a symptom of lowered vitality expressed in terms of the mind. There is a philosophical Pessimism, as I have already said, over and above all merely physical conditions, and not dependent on them. But the melancholy Jacques of our ordinary experience either uses some narcotic or stimulant to excess, or else has trouble with his liver or kidneys. "Liver complaint," says Zangwill, "is the Prometheus myth done into modern English." Already historical criticism has shown that the Bloody Assizes had its origin in disease of the bladder, and most forms of vice and cruelty resolve themselves into decay of the nerves. It is natural that degeneration should bring discouragement and disgust. But whatever the causes of Pessimism, whether arising in speculative philosophy in nervous disease or in personal failure, it can never be wrought into sound and helpful life. To live effectively implies the belief that life is worth living, and no one who leads a worthy life has ever for a moment doubted this. Such an expression as "worth living" has in fact no real meaning. To act and to love are the twin functions of the human body and soul. To refuse these functions is to make one's self incapable of them. It is in a sense to die while the body is still alive. To refuse these functions is to make misery out of existence, and a life of ennui is doubtless not "worth living."