Sex, therefore, in the human race alone, resting upon that broad, well-marked mental foundation, is capable of great development towards good or towards evil. As simply material satisfaction soon reaches the limit which bounds matter, so mental or spiritual enjoyment is capable of indefinite growth. It is this mental sentiment peculiar to human sex which is capable of a twofold development. It may grow into a noble sympathy, self-sacrifice, reverence, and joy, which enlarge and intensify the nature through the gradual expansion of the inborn moral elements of sex. It is also this same intensity of the mental form and power of sex, possessed by mankind alone, which allows of the perversion and extreme degradation of sex which is observable only in the human race. It is the degradation of this mental power when running riot in unchecked license that converts men and women into selfish and cruel devils--monsters, quite without parallel in the brute creation. These facts are strikingly illustrated by the anatomical and physiological constitution of the human being. The structure and functions of the generative system in our race are contrived in such a way as to support two great leading principles of existence. These fundamental principles are--First, the independence, freedom, and perfection of the individual. Second, the preservation of the race. These two objects are secured to a certain extent in all highly organized creatures; but in the human race provision is made for individual freedom in a much more marked and perfect manner, in accordance with the superior rank of man in creation. The brute, both male and female, is at certain times blindly dominated by the physical impulse of sex. This impulse in the lower animal is a simple imperative instinct, unhesitatingly yielded to, with no preparation or after-thought, with no calculation, shame, triumph, or regret. But it is very different with the human race, as it grows from lower to higher states of society. Thoughts and feelings, social ties and conscience, religious training and the objects of life, all act upon the distinctive mental character of sex; and it is seen that the welfare of a third factor, viz., the child, is inseparably connected with these relations. Its character is thus changed to a very complex faculty. The young man or woman blindly yielding to this power of sexual attraction, against the remonstrance of a high sense of duty, is torn by remorse, and is consciously self-degraded. The influence of the moral element is also strikingly shown by an evil peculiar to the human race, viz., suicide or insanity as the result of unhappy love.