The presumed necessity for physical compulsion did not stop at slavery. As we have already seen, it was accepted as an axiom in statecraft that men's religious beliefs had to be forcibly restrained, and not merely their religious belief, but their very clothing; and we have hundreds of years of complicated sumptuary laws, hundreds of years, also, of forcible control or, rather, the attempted forcible control of prices and trade, the elaborate system of monopolies, absolute prohibition of the entrance into the country of certain foreign goods, the violation of which prohibition was treated as a penal offence. We had even the use of forced money, the refusal to accept which was treated as a penal offence. In many countries for years it was a crime to send gold abroad, all indicating the domination of the mind of man by the same curious obsession that man's life must be ruled by physical force, and it is only very slowly and very painfully that we have arrived at the truth that men will work best when left to unseen and invisible forces. A world in which physical force was withdrawn from the regulation of men's labor, faith, clothes, trade, language, travel, would have been absolutely inconceivable to even the best minds during the three or four thousand years of history which mainly concern us. What is the central explanation of the profound change involved here--the shifting of the pivot in all human affairs, in so far as they touch both the individual and the community, from physical ponderable forces to economic imponderable forces? It is surely that, strange as it may seem, the latter forces accomplish the desired result more efficiently and more readily than do the former, which even when they are not completely futile are in comparison wasteful and stultifying. It is the law of the economy of effort. Indeed, the use of physical force usually involves in those employing it the same limitation of freedom (even if in lesser degree) as that which it is desired to impose. Herbert Spencer illustrates the process in the following suggestive passage: The exercise of mastery inevitably entails on the master himself some sort of slavery more or less pronounced. The uncultured masses and even the greater part of the cultured will regard this statement as absurd, and though many who have read history with an eye to essentials rather than to trivialities know that this is a paradox in the right sense--that is, true in fact though not seeming true--even they are not fully conscious of the mass of evidence establishing it, and will be all the better for having illustrations recalled. Let me begin with the earliest and simplest which serves to symbolize the whole.