THE WEALTH OF NATIONS.

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have introduced and established this policy are explained inthe Third Book.

Though those different plans were, perhaps, first introducedby the private interests and prejudices of particular orders ofmen, without any regard to, or foresight of, their conse-quences upon the general welfare of the society; yet theyhave given occasion to very different theories of politicaleconomy; of which some magnify the importance of that in-dustry which is carried on in towns, others of that which iscarried on in the country. Those theories have had a con-siderable influence, not only upon the opinions of men oflearning, but upon the public conduct of princes and sove-reign states. I have endeavoured, in the Fourth Book, to ex-plain, as fully and distinctly as I can, those different theories,and the principal effects which they have produced in dif-ferent ages and nations.

To explain in what has consisted the revenue of the greatbody of the people, or what has been the nature of those funds,which, in different ages and nations, have supplied their an-nual consumption, is the object of these Four first Books.The Fifth and last Book treats of the revenue of the sovereign,or commonwealth. In this Book I have endeavoured to shew,first, what are the necessary expenses of the sovereign, orcommonwealth; which of those expenses ought to be de-frayed by the general contribution of the whole society; andwhich of them by that of some particular part only, or of someparticular members of it: secondly, what are the differentmethods in which the whole society may be made to contri-bute towards defraying the expenses incumbent on the wholesociety, and what are the principal advantages and inconve-niencies of each of those methods: and, thirdly and lastly,what are the reasons and causes which have induced almostall modern governments to mortgage some part of this re-venue, or to contract debts, and what have been the effects ofthose debts upon the real wealth, the annual produce of theland and labour of the society.