Permanent mating is altruistic in character, but the altruism extends only to the future generation. Even the fastidiousness found in permanent mating is in the interest of the unborn. The mates are only tools in the hands of the commanding Spirit, whose all-governing principle has only one thought, only one prosaic aim, the propagation of the human species. The attachment between both mates cannot, therefore, be properly called love. For in love the mate is of primary importance. But the permanent-mating impulse is the stepping-stone to love which is first found in the human race. In human love a distinction must be made, according to Finck, between two different kinds; love as an instinct, or sensual love[AD] and love as a sentiment, or sentimental love. Sensual love is the only kind of love the greater part of humanity knows.[AE] This love has no depth or duration, and when satisfied, cares no longer for the object for which it temporarily hungered. For when sense forms the chief part of the compound feeling, love will not long survive possession. There may be a strong individual preference in sensual love. The charm exuding from the personality of one individual may possess a kind of personal magnetism for another of the opposite sex. The luscious intoxicating essences, exhaling from one person, may have a particular idiosyncratical attraction for the other. Hence sensual love may be as fastidious as pure love. It may temporarily focus its interest on one person only. Yet in sensual love the intense desire for exclusive possession, the jealousy toward rivals, the coy-resistance, and the moods of doubt and hope are only emanations of selfish lust, of eagerness to gratify an appetite with a particular victim for whom the lover has no adoration or self-sacrificing devotion. Such a lover loves only himself; his one object is to please his own beloved “I,” without any regards for the feelings of his mate. The latter figures only as a means to the end, that end being his own gratification. To such a lover, “I love you” means “I long for you, covet you, and am eager to enjoy you.” All indulgences and favors shown to the mate are only meant as means to gain a certain end, and when this cannot be attained, sensual love will change into the contrary passion of hatred. In sentimental love such a thing as hatred is impossible. For to understand a thing thoroughly, forever puts that thing beyond the pale of hatred; to love a thing merely is to subject oneself to the possibility of hating that thing.