A second implication is important. My thesis involves the view that if in any state there is a body of men who possess unlimited political power, those over whom they rule can never be free. For the one assured result of historical investigation is the lesson that uncontrolled power is invariably poisonous to those who possess it. They are always tempted to impose their canon of good upon others, and, in the end, they assume that the good of the community depends upon the continuance of their power. Liberty always demands a limitation of political authority, and it is never attained unless the rulers of a state can, where necessary, be called to account. That is why Pericles insisted that the secret of liberty is courage. By making liberty the absence of restraint, I make it, of course, a purely negative condition. I do not thereby mean to assume that a man will be the happier the more completely restraints are absent from the society to which he belongs. In a community like our own, the pressure of numbers and the diversity of desires, make necessary both rules and compulsions. Each of these is a limitation upon freedom. Some of them are essential to happiness, but that does not make them for a moment less emphatically limitations. Our business is to secure such a balance between the liberty we need and the authority that is essential as to leave the average man with the clear sense that he has elbow-room for the continuous expression of his personality. Nor must we confound liberty with certain other goods without which it has no meaning. There may be absence of restraint in the economic sphere, for example, in the sense that a man may be free to enter any vocation he may choose. Yet if he is deprived of security in employment he becomes the prey of a mental and physical servitude incompatible with the very essence of liberty. Nevertheless, economic security is not liberty though it is a condition without which liberty is never effective. I do not mean that those who can take their ease in Zion are thereby free men. Once and for all, let us agree that property alone does not make a man free. But those who know the normal life of the poor, its perpetual fear of the morrow, its haunting sense of impending disaster, its fitful search for beauty which perpetually eludes, will realize well enough that, without economic security, liberty is not worth having. Men may well be free and yet remain unable to realize the purposes of freedom.