The great question of taxation we may only mention here by way of exclusion. It is naturally a matter for treatment by itself. The reader will remember (see chapter VII) that nearly all the States have now inheritance taxes besides direct property taxes, and many of them have income taxes and, in the South particularly, license taxes, or taxes upon trades or callings. They all tax corporations, nearly always by an excise tax on the franchise or stock, distinct from the property tax or the tax upon earnings. In both corporation taxes and inheritance taxes they are likely to find themselves in conflict with the Federal government, or at least to have duplicate systems taxing the same subjects, as, indeed, already considerable injustice is caused by inheritance taxes imposed in full in each State upon the stock of corporations lying in more than one State. In such cases the tax should, of course, be proportionate. The principle of graded taxation in the matter of incomes and succession taxes has been very generally adopted, not as yet in any direct property tax, except that a small amount of property, one hundred dollars or five hundred dollars, is usually exempt. The principle of imposing taxation not for revenue, but for some ulterior or ethical purpose, such as the destruction of swollen fortunes, is liable to constitutional objection in this country, though the courts may not look behind the tax to the motive, unless the latter is expressed upon the face. For this reason, the present corporation tax, on its surface, is imposed solely for the purpose of raising revenue, though in debate in Congress it was advocated mainly for the object of bringing large corporations under Federal examination and control.