With the enactment of the Income Tax Law of 1913, the Federal Government began to apply effectively the widely accepted principle that taxes should be levied in proportion to ability to pay and in proportion to the benefits received. Income was wisely chosen as the measure of benefits and of ability to pay. This was, and still is, a wholesome guide for national policy. It should be retained as the governing principle of Federal taxation. The use of other forms of taxes is often justifiable, particularly for temporary periods; but taxation according to income is the most effective instrument yet devised to obtain just contribution from those best able to bear it and to avoid placing onerous burdens upon the mass of our people.
Message to Congress on Tax Revision (June 19, 1935)