The rule that the greatest possible happiness of _all_ is to be striven for, is an assertion that the happiness of every one is to be considered, that not that of the lowest human being is to be interfered with unless such interference is _necessary_ in order to prevent still greater harm to others; and that no such interference shall be greater than is positively necessary in accordance with this aim. The highest moral law is thus nothing more than the Christian commandment of love to all men. And the rule "To count each as one, no more," may receive the restrictive clause "in so far as the good of the whole of society is not diminished by so doing." Some Darwinians are inclined to regard the preservation of existence as the criterion by which to judge the moral quality of action. "Aim for the preservation of the species" would be, from their standpoint, the moral law. But mere existence is not happiness; that is shown by the fact of suicide. However, it is true that health is one of the conditions of happiness. Pessimists are generally men of an unhappy temperament, often of morbid physical constitution; medical science must, in its progress, help to prevent the development of such morose dispositions. Want of love may also be a cause of pessimism; most pessimists have been lonely men. And want of employment may also lead to pessimism. If we follow Rousseau's advice not to listen to those who are in exceptional abnormal positions, but appeal to those who constitute the great majority, we shall conclude that, in general, the happiness of men greatly exceeds their misery. The increase of suicide is often used as an argument that civilization has not caused an increase, but a decrease, of happiness. To this argument it may be answered that the religious scruples which formerly withheld men from this extreme step have diminished, that men have grown more self-conscious and independent in action; and that, moreover, our age is one of unrest, a transition-period such as no other period has been. When we examine the lives of tribes on a low plane of civilization, we find their existence full of uncertainty and of superstitious fear, and at the mercy of the forces of nature. Without doubt, much misery exists; a great part of it, however, is caused by the disappointment of too extreme demands for happiness; the individual must not require that life shall be continuous rapture. The recognition of what right action is, is not its accomplishment. Pain and pleasure determine the will,--the pain and pleasure of the person who wills, since he cannot feel with the feelings of others or will with their will any more than he can move with their limbs. He may have a conception of the welfare or suffering of others, but a mere mental image does not determine the will. Only when such a conception arouses pleasure or pain in the subject himself, are will and action possible.