The key to this attitude is clear enough. The improvement of society is due, he thinks not to the calculations of government but to the natural instincts of economic man. We cannot avoid the impulse to better our condition; and the less its effort is restrained the more certain it is that happiness will result. We gain, in fact, some sense of its inherent power when we bear in mind the magnitude of its accomplishment despite the folly and extravagance of princes. Therein we have some index of what it would achieve if left unhindered to work out its own destinies. Human institutions continually thwart its power; for those who build those institutions are moved rather "by the momentary fluctuations of affairs" than their true nature. "That insidious and crafty animal, vulgarly called a politician or statesman" meets little mercy for his effort compared to the magic power of the natural order. "In all countries where there is a tolerable security," he writes, "every man of common understanding will endeavor to employ whatever stock he can command in procuring either present enjoyment or future profit." Individual spontaneity is thus the root of economic good; and the real justification of the state is the protection it affords to this impulse. Man, in fact, is by nature a trader and he is bound by nature to discover the means most apt to progress. Nor was he greatly troubled by differences of fortune. Like most of the Scottish school, especially Hutcheson and Hume, he thought that men are much alike in happiness, whatever their station or endowments. For there is a "never-failing certainty" that "all men sooner or later accommodate themselves to whatever becomes their permanent situation"; though he admits that there is a certain level below which poverty and misery go hand in hand. But, for the most part, happiness is simply a state of mind; and he seems to have had but little suspicion that differences of wealth might issue in dangerous social consequence. Men, moreover, he regarded as largely equal in their original powers; and differences of character he ascribes to the various occupations implied in the division of labor. Each man, therefore, as he follows his self-interest promotes the general happiness of society. That principle is inherent in the social order. "Every man," he wrote in the _Moral Sentiments_, "is by nature first and principally recommended to his own care" and therein he is "led by an invisible hand to promote an end which was no part of his intention." The State, that is to say, is the sum of individual goods; whereby to better ourselves is clearly to its benefit. And that desire "which comes with us from the womb and never leaves us till we go to the grave" is the more efficacious the less it is restrained by governmental artifice. For we know so well what makes us happy that none can hope to help us so much as we help ourselves.