Spencer’s explanation is pure theory, based as it is not upon observation of particular facts, but upon a knowledge of certain physiological laws. Darwin’s explanation, on the contrary, is evidently based on very careful observations of particular instances of the manifestation of the primitive musical faculty. Nevertheless, however interestingly Darwin writes concerning the origin of music, Spencer’s explanation must seem to us the broader, more inclusive and satisfying of the two, inasmuch as it bases the origin of music in a variety of emotional experiences rather than in only one (the love emotion). Darwin, however, says that the emotion of love may give rise to many other emotions of a quite different character, such as rage, jealousy, and triumph; and proceeds to indicate the possible development of various kinds of primitive songs from primitive love songs. It is, however, difficult for us to conceive of the development of war songs, incantations, or howls of grief for the dead as having been developed from primitive love songs. According to Grosse, music arose from the play instinct. It is one of the forms in which superabundant energy is spent. Most animals, including man, are endowed with more than enough energy than is absolutely necessary to supply their physical needs. This superabundant energy is expressed in different kinds of play. The leaping and diving of the porpoise, the gambolling of dogs, the running of races, and the playing of games among primitive men are examples of the working of the play instinct. Our modern sports, tennis, football, etc., are also examples of it. According to this theory, singing and dancing first arose as means of diversion from the monotony of existence, as a means of whiling away the time and making life pleasant. This is a most important theory, and while it probably is not wholly true, it contains a large percentage of truth. It is upheld by a great number of writers besides Grosse, and has great significance concerning the origin of all the Arts, including music.