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).
It is a familiar observation that the mothers of large families of ten and even twice that number are not less healthy nor shorter lived because of the children they have borne. Pregnancy is a stimulus to vitality. Because another life has to be supported, all the vital powers are invigorated and rise to the occasion—the circulation increases, the heart enlarges in response to the extra work, and the assimilative powers of the body are greatly accelerated. During lactation also, the same extra vital work done is a stimulus to a physiological activity which is favourable to health and longevity. The expectancy of life in women is greater than in men all through life, the difference during the child-bearing period of life being about 2.2 years in favour of women.
Statistics and physicians from their observation agree in this, that the bearing of children by normal women, so far from being injurious to health, is as healthful, stimulating, and invigorating a function as the blooming of a flower, or the shedding of fruit, and a mother is no worse for the experience of maternity than is the plant or the tree for the fruit it bears.
The supreme law of society is the law of race-preservation, and the infraction of this law is a social crime. One's duty to society is a higher duty than to one's-self, but the lower duty comes first in our present stage of racial evolution. Instinct prompts to the one, reason—a higher and later, but less respected, faculty—prompts to the other.
But it can be shown that from an egoistic standpoint my duty to the State in this regard is my highest duty to myself.