"In his discussion on slavery Aristotle said that when the shuttle wove by itself and the plectrum played by itself chief workmen would not need helpers nor masters slaves. At the time he wrote, he believed that he was establishing the eternal validity of slavery; but for us today he was in reality justifying the existence of the machine. Work, it is true, is the constant form of man's interaction with his environment, if by work one means the sum total of exertions necessary to maintain life; and the lack of work usually means an impairment of function and a breakdown in organic relationship that leads to substitute forms of work, such as invalidism and neurosis. But work in the form of unwilling drudgery or of that sedentary routine which... the Athenians so properly despised—work in these forms is the true province of machines. Instead of reducing human beings to work-mechanisms, we can now transfer the main part of burden to automatic machines. This potentially... is perhaps the largest justification of the mechanical developments of the last thousand years."