ities used by public utilities do become a minor factor in the calculation. When on the other hand War or other cause makes the commodities used a superior factor, the system must break down, because of this overmastering difficulty. So it was absolutely necessary for the Government, no matter at what cost, to take over the railroads during the great conflict, in order that there might not be a complete collapse of national sustenance. It can, therefore, easily be seen why there is so much complaint, and so little defense of the excess profits tax, for when the matter is reduced to its fundamental principles, it is found that these taxes are but a depletion of what really is the fund that insures the continuance of the life of American trade. The panic, therefore, that may result from so uneconomic a method of taxation, may easily be of the most disastrous character in our history.
It may be well in this connection, though it involves restatement, to recapitulate some of the leading principles which it has been the endeavor to establish in the preceding chapters. Had any student of economic principle been told that since Adam Smith published his work, in 1776, there could possibly be a recrudescence of the theories of the mercantile system, he would not have been believed. And yet, that is exactly what is taking place and constitutes the chief difficulty in the cases that have been before the courts. To say that such a difficult economic problem can be reduced to the simple formula: "What did you pay for a specific lot of goods in money, and how much did you get for it in money" is to make the most complex question imaginable one of the utmost simplicity. Indeed, it is almost as simple as it is impracticable and erroneous. It might have been safely assumed that in this day, at least, every one was aware "that all trade in the
