Sufficient has now been said to indicate--but scarcely more than indicate--the importance of feeling-tone, interest, and emotion in determining the nature, character, and effective energy of the conscious situations which arise in the course of animal behaviour. They largely influence, and in part direct, the course of the conative tendency. But they also occur as its sequel. In animal, as in human life, the successful attainment of the end towards which conation sets is highly pleasurable. The equilibrium that is reached after instability, though it marks the close of present endeavour, leaves after-effects in consciousness in a sense of satisfaction which enters re-presentatively into later situations and helps to further more strenuous endeavour. II.--PLAY “There are two quite different popular ideas of play,” says Professor Groos, in his admirable work on “The Play of Animals.” “The first is that the animal (or man) begins to play when he feels particularly cheerful, healthy, and strong; the second that the play of young animals serves to fit them for the tasks of later life.” The former view, in which the latter may be included incidentally as a result, is closely associated with the names of Schiller,[123] who suggested it, and of Mr. Herbert Spencer,[124] who developed it. Mr. Wallaschek[125] expresses the conception briefly and clearly when he says, “It is the surplus vigour in more highly developed organisms, exceeding what is required for immediate needs, in which play of all kinds takes its rise, manifesting itself by way of imitation or repetition of all those efforts and exertions which are essential to the maintenance of life.” That surplus vigour is often a condition favouring the manifestation of play is probable enough, and seems to be supported by observation and experience; but that it is likewise a condition favouring the chase, combat, mating, and much of the serious business of animal life seems equally unquestionable. Success in all these matters is largely determined by overflowing energy. In play, however, this surplus vigour finds vent when there is no serious occasion for its exercise. But, as Professor Groos says,[126] “while simple overflow of energy explains quite well that the individual who finds himself in a condition of overflowing energy is ready to do something, it does not explain how it happens that all the individuals of a species manifest exactly the specific kind of play expression which prevails with their own species, but differs from every other.” And if to this it be replied, that the specific kind is determined by repetition or imitation of what we have called the serious business of animal life, Professor Groos’s rejoinder is,[127] that “the conception of imitation here set forth--namely, as the repetition of serious activities to which the individual has himself become accustomed--cannot be applied directly to the primary phenomena of play--that is, to its first elementary manifestations”