Life is dominated by the urge of self-preservation and by sexual urge. The former preserves the individual, the latter the race. For biological purposes racial preservation is more urgent than individual survival, therefore the urge of sex is stronger than hunger, stronger than fear. Among animals, the most apt and vigorous males are the first to risk their lives in nuptial combats for their mates; the same is true of primitive man. And in civilization we may daily observe that human beings expose themselves to all possible danger and difficulties in order to satisfy this imperious longing, and frequently sacrifice life itself on the Altar of Love.