"Society could not have come into existence or been preserved without a harmony of the rightly understood interests of all its members."

"[T]he gain of one man is [said to be] the damage of another; no man profits but by the loss of others... [Yet] society could not have come into existence or been preserved without a harmony of the rightly understood interests of all its members....
    "Human effort exerted under the principle of the division of labour in social cooperation achieves, other things remaining equal, a greater output per unit of input than the isolated efforts of solitary individuals. Man's reason is capable of recognising this fact and of adapting his conduct accordingly. Thus social cooperation becomes for almost every man the great means for the attainment of all ends. An eminently human common interest, the preservation and intensification of social bonds, is substituted for pitiless biological competition, the significant mark of animal and plant life. Man becomes a social being. He is no longer forced by the inevitable laws of nature to look upon all other specimens of his animal species as deadly foes. Other people become his fellows. For animals the generation of every new member of the species means the appearance of a new rival in the struggle for life. For man, until the optimum size of population is reached, it means rather an improvement than a deterioration in his quest for material well-being."

~ Ludwig von Mises, compilation quote from his 1949 book Human Action, and his 1957 book Theory and History [hat tip Daniel Sanchez's article 'The Profound Significance of Social Harmony']