In these essays, the author tried to set forth, as clearly as possible, certain fundamental principles, together with their practical application to the life of our time. Some of these principles were stated, more briefly and technically, in Ellis's larger Studies of sex; others were therein implied but only to be read between the lines. Here they are expressed in simple language and with some detail. Contents: children and parents; meaning of purity; objects of marriage; husbands and wives; love rights of women; play function of sex; individual and the race.