There are, however, two different circumstances which render the interest of money a much less proper subject of direct taxation than the rent of land.
First, the quantity and value of the land which any man possesses can never be a secret, and can always be ascertained with great exactness. But the whole amount of the capital stock which he possesses is almost always a secret, and can scarce ever be ascertained with tolerable exactness. It is liable, besides, to almost continual variations. A year seldom passes away, frequently not a month, sometimes scarce a single day, in which it does not rise or fall more or less. An inquisition into every man’s private circumstances, and an inquisition which, in order to accommodate the tax to them, watched over all the fluctuations of his fortunes, would be a source of such continual and endless vexation as no people could support.
Secondly, land is a subject which cannot be removed; whereas stock easily may. The proprietor of land is necessarily a citizen of the particular country in which his estate lies. The proprietor of stock is properly a citizen of the world, and is not necessarily attached to any particular country. He would be apt to abandon the country in which he was exposed to a vexatious inquisition, in order to be assessed to a burdensome tax, and would remove his stock to some other country where he could either carry on his business, or enjoy his fortune more at his ease. By removing his stock he would put an end to all the industry which it had maintained in the country which he left. Stock cultivates land; stock employs labour. A tax which tended to drive away stock from any particular country would so far tend to dry up every source of revenue both to the sovereign and to the society. Not only the profits of stock, but the rent of land and the wages of labour would necessarily be more or less diminished by its removal.
The nations, accordingly, who have attempted to tax the revenue arising from stock, instead of any severe inquisition of this kind, have been obliged to content themselves with some very loose, and, therefore, more or less arbitrary, estimation. The extreme inequality and uncertainty of a tax assessed in this manner can be compensated only by its extreme moderation, in consequence of which every man finds himself rated so very much below his real revenue that he gives himself little disturbance though his neighbour should be rated somewhat lower.