… is from page 54 of the 2006 Liberty Fund edition of Ludwig von Mises’s 1956 volume, The Anti-capitalistic Mentality (available free-of-charge on-line here):
Social cooperation under the division of labor is the ultimate and sole source of man’s success in his struggle for survival and his endeavors to improve as much as possible the material conditions of his well-being.
DBx: Protectionists aim to stymie social cooperation under the division of labor.