Retributive kindly emotion is a much less frequent phenomenon in the animal kingdom than is the emotion of resentment. In many animal species not even the germ of it is found, and where it occurs it is generally restricted within narrow limits. Anybody may provoke an animal's anger, but only towards certain individuals it is apt to feel retributive kindliness. The limits for this emotion are marked off by the conditions under which altruistic sentiments in general tend to arise--a subject which will be discussed in another connection. Indeed, social affection is itself essentially retributive. Gregarious animals take pleasure in each other's company, and with this pleasure is intimately associated kindly feeling towards its cause, the companion himself. Social affection presupposes reciprocity; it is not only a friendly sentiment towards another individual, but towards an individual who is conceived of as a friend. The intrinsic object of retributive kindliness being to retain a cause of pleasure, we may assume that the definite desire to produce pleasure in return for pleasure received is due to the fact that such a desire materially promotes the object in question--exactly in the same way as the definite desire to inflict pain in return for pain inflicted has become an element in resentment because such a desire promotes the intrinsic object of resentment, the removal of the cause of pain. And as natural selection accounts for the origin of resentment, so it also accounts for the {95} origin of retributive kindly emotion. Both of these emotions are useful states of mind; by resentment evils are averted, by retributive kindliness benefits are secured. That there is such a wide difference in their prevalence is explicable from the simple facts that gregariousness--which is the root of social affection, and, largely at least, a condition of the rise of retributive kindly emotions--is an advantage only to some species, not to all, and that even gregarious animals have many enemies, but few friends. In some cases the friendly reaction in retributive kindliness is directed towards individuals who have in no way been the cause of the pleasure which gave rise to the emotion. So intimate is the connection between the stimulus and the reaction, that he who is made happy often feels a general desire to make others happy.[97] But such an indiscriminate reaction is only an offset of the emotion with which we are here concerned. Moreover, retributive kindly emotion often confers benefits upon somebody nearly related to the benefactor, if he himself be out of reach, or in addition to benefits conferred on him. But in such cases the gratitude towards the benefactor is the real motive. [Footnote 97: That a happy man wants to see glad faces around him, is also due to another cause, which has been pointed out by Dr. Hirn (_Origins of Art_, p. 83): from their expression he wants to derive further nourishment and increase for his own feeling.]