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.