Thus, in order to understand the connection between love and pain, we have once more to return to the consideration, under a somewhat new aspect, of the fundamental elements in the sexual impulse. In discussing the "Evolution of Modesty" we found that the primary part of the female in courtship is the playful, yet serious, assumption of the rôle of a hunted animal who lures on the pursuer, not with the object of escaping, but with the object of being finally caught. In considering the "Analysis of the Sexual Impulse" we found that the primary part of the male in courtship is by the display of his energy and skill to capture the female or to arouse in her an emotional condition which leads her to surrender herself to him, this process itself at the same time heightening his own excitement. In the playing of these two different parts is attained in both male and female that charging of nervous energy, that degree of vascular tumescence, necessary for adequate discharge and detumescence in an explosion by which sperm-cells and germ-cells are brought together for the propagation of the race. We are now concerned with the necessary interplay of the differing male and female rôles in courtship, and with their accidental emotional by-products. Both male and female are instinctively seeking the same end of sexual union at the moment of highest excitement. There cannot, therefore, be real conflict.[63] But there is the semblance of a conflict, an apparent clash of aim, an appearance of cruelty. Moreover,--and this is a significant moment in the process from our present point of view,--when there are rivals for the possession of one female there is always a possibility of actual combat, so tending to introduce an element of real violence, of undisguised cruelty, which the male inflicts on his rival and which the female views with satisfaction and delight in the prowess of the successful claimant. Here we are brought close to the zoölogical root of the connection between love and pain.[64] In his admirable work on play in man Groos has fully discussed the plays of combat (_Kampfspiele_), which begin to develop even in childhood and assume full activity during adolescence; and he points out that, while the impulse to such play certainly has a wider biological significance, it still possesses a relationship to the sexual life and to the rivalries of animals in courtship which must not be forgotten.[65]