the most important of all markets for the rude produce of the land, and thereby still further to discourage agriculture.

Those systems, therefore, which, preferring agriculture to all other employments, in order to promote it, impose restraints upon manufactures and foreign trade, act contrary to the very end which they propose, and indirectly discourage that very species of industry which they mean to promote. They are so far, perhaps, more inconsistent than even the mercantile system. That system, by encouraging manufactures and foreign trade more than agriculture, turns a certain portion of the capital of the society from supporting a more advantageous, to support a less advantageous species of industry. But still it really and in the end encourages that species of industry which it means to promote. Those agricultural systems, on the contrary, really and in the end discourage their own favourite species of industry.

It is thus that every system which endeavours, either by extraordinary encouragements to draw towards a particular species of industry a greater share of the capital of the society than what would naturally go to it, or, by extraordinary restraints, force from a particular species of industry some share of the capital which would otherwise be employed in it, is in reality subversive of the great purpose which it means to promote. It retards, instead of accelerating, the progress of the society towards real wealth and greatness; and diminishes, instead of increasing, the real value of the annual produce of its land and labour.

All systems either of preference or of restraint, therefore, being thus completely taken away, the obvious and simple system of natural liberty establishes itself of its own accord. Every man, as long as he does not violate the laws of justice, is left perfectly free to pursue his own interest his own way, and to bring both his industry and capital into competition with those of any other man, or order of men. The sovereign is completely discharged from a duty, in the attempting to perform which he must always be exposed to innumerable delusions, and for the proper performance of which no human wisdom or knowledge could ever be sufficient; the duty of superintending the industry of private people, and of directing it towards the employments most suitable to the interest of the society. According to the system of natural liberty, the sovereign has only three duties to attend to; three duties of great importance, indeed, but plain and intelligible to common understandings: first, the duty of protecting the society from violence and invasion of other independent societies; secondly, the duty of protecting, as far as possible, every member of the society from the injustice or oppression of every other member of it, or the duty of establishing an exact administration of justice; and, thirdly, the duty of erecting and maintaining certain public works and certain public institutions which it can never be for the interest of any individual, or small number of individuals, to erect and maintain; because the profit could never repay the expense to any individual or small number of individuals, though it may frequently do much more than repay it to a great society.

The proper performance of those several duties of the sovereign necessarily supposes a certain expense; and this expense again necessarily requires a certain revenue to support it. In the following book, therefore, I shall endeavour to explain, first, what are the necessary expenses of the sovereign or commonwealth; and which of those expenses ought to be defrayed by the general contribution of the whole society; and which of them by that of some particular part only, or of some particular members of the society; secondly, what are the different methods in which the whole society may be made to contribute towards defraying the expenses incumbent on the whole society, and what are the principal advantages and inconveniences of each of those methods; and thirdly, what are the reasons and causes which have induced almost all modern governments to mortgage some part of this revenue, or to contract debts, and what have been the effects of those debts upon the real wealth, the annual produce of the land and labour of the society. The following book, therefore, will naturally be divided into three chapters.