Taking animal life as a whole it is at least clear that what are called the self-regarding feelings must come first in order of development. Even with the lower races of human beings there is less concern shown with the feelings and welfare of others than is the case with the higher races of men. Or, again, with children we have these feelings strongest in childhood and undergoing a gradual expansion as maturity is reached. This is brought about, as was shown in the last chapter, not by the destruction of existing feelings, but by their extension to an ever widening area. There is a transformation, or an elaboration of existing feelings under the pressure of social growth. One may say that ethical development does not proceed by the destruction of the feeling of self-interest, so much as by its extension to a wider field. Ethical growth is thus on all fours with biological growth. In biology we are all familiar with the truth that maintenance of life is dependent upon the existence of harmonious relations between an organism and its environment. Yet it is not always recognized that this principle is as true of the moral self as it is of the physical structure, nor that in human evolution the existence of others becomes of increasing importance and significance. For not only do I have to adapt myself, mentally and morally, to the society now existing, but also to societies that have long since passed away and have left their contribution to the building up of _my_ environment in the shape of institutions and beliefs and literature. We have in this one more illustration that while the environment of the animal is overwhelmingly physical in character, that of man tends to become overwhelmingly social or psychological. Desires are created that can only be gratified by the presence and the labour of others. Feelings arise that have direct reference to others, and in numerous ways a body of "altruistic" feeling is created. So by social growth first, and afterwards by reflection, man is taught that the only life that is enjoyable to himself is one that is lived in the companionship and by the co-operation of others. As Professor Ziegler well puts the process:--