It is interesting to find that it is the intuitive, not the inductive, element of the moral attributes that we find principally developed in the lower animals. This is the outgrowth of instinct, not of thought; the development of that principle of attraction which manifests itself in all nature, and which, when associated with consciousness, becomes what we know as love, affection, or sympathy. It is a powerful and pervading force in all matter, intelligent and unintelligent, and in conscious beings falls naturally among the emotions. Like all the passions, it is instinctive in origin, though it may come under the control of the intellect as the mind develops. In the lower animal world it is manifested as a vigorous attraction, the sexual. In the higher animals this attraction expands and grows complex. The attraction between the sexes becomes love, and in its full unfoldment may join two individuals together for life and influence most of their actions. To the attraction between the sexes should be added that between parents and children, the parental and filial, and that between associates, the tribal or social, the latter, though weaker, of the same character. With these bonds reason has nothing to do. It does not form them and would seek in vain to sever them. They belong to a part of the mental constitution which lies outside the kingdom of thought, and they, therefore, often act counter to the selfish consideration of personal safety. The love bond, indeed, in its full strength, seems to constitute a partial loss of individuality. Mates will suffer pain and endure physical injury for each other or for their offspring to as great an extent as if these constituted a part of themselves, and as if their actions were performed in self-defence. With this brief review of the philosophy of the ethical sentiments, we may proceed to a consideration of the facts. While the rudimentary form of the sentiment in question is manifest far down in the descending grades of animal life, it expands into what we may fairly term love or affection only in the higher forms. Romanes, in his "Animal Intelligence," remarks: "As regards emotions, it is among birds that we first meet with a conspicuous advance in the tenderer feelings of affection and sympathy. Those relating to the sexes and the care of progeny are in this class proverbial for their intensity, offering, in fact, a favorite type for the poet and moralist. The pining of the 'love-bird' for its absent mate, and the keen distress of a hen on losing her chickens, furnish abundant evidence of vivid feelings of the kind in question. Even the stupid-looking ostrich has heart enough to die for love, as was the case with a male in the Rotund of the Jardin des Plantes, who, having lost his mate, pined rapidly away."