My first thought is for myself, and my duty is to increase the sum of my happiness. But the mental state we call happiness is relative to the presence or absence of this state in others. Even amongst the lower animals, misery and distress in one of the flock militate against the happiness of the others. In a highly developed man true happiness is impossible in the presence of pain and misery in others and _vice versa_; happiness is contagious and flows to us from the joy of others. If the happiness of others then is so essential to my own happiness, I am fulfilling the first law of life and ministering to my own preservation in health and happiness by using my best endeavours to promote this state in others. My material comfort too depends largely on the labour, and love, and the contribution of others in the complex industrial system and division of labour of the higher civilisations. Not only my happiness and health but my very existence depends on the good-will and toil of others. Thus from a purely egoistic standpoint, my first duty to myself is to increase the happiness in others, and, therefore, my first duty to myself becomes my highest duty to society. My duty to my child is comprehended in my duty to society, _i.e._, to others. My duty to others is to increase the sum of the happiness of others, and bringing healthy children into the world not only creates beings capable of experiencing and enjoying pleasures, but adds to the sum of social happiness, by increasing the number of social units capable of rendering service to others. The next great law of life is the law of race preservation. This law comprises the instinct to reproduction and the instinct of parental love. The first and chief function of these instincts in the animal economy is the perpetuation of the race. The preservation of self implies and comprehends the preservation of the race. My first duty to myself is to preserve myself in health and happiness; but this is best fulfilled and realized in labouring for the health and happiness of others. If this be the universal law, I also am the recipient of others' care, therefore probably better tended and preserved. I save my life by losing it in others. My second duty, though nominally to Society, is in reality to myself, and it is to preserve myself by preserving the race to which I belong. Self-preservation therefore, is the first law of life, race preservation the second or subsidiary law. To fulfil this second law, nature has placed on every normal healthy man and woman the sacred duty of reproducing their kind. Reproduction as a physiological process promotes, both directly and indirectly, the health, happiness and longevity of healthy men and women. Statistics confirm the popular opinion "that the length of life, to the enjoyment of which a married person may look forward, is greater than that of the unmarried, both male and female at the same age."--(Coghlan).