"The income tax completely destroys the immunity of property. It flatly declares a prior right of the State to all things produced. What it permits the individual to retain is a concession to expediency, not by any means a right; for the State retains the liberty to set rates and to fix exemptions from year to year, as its convenience dictates. Thus, the sacred right of private property is violated, and the fact that it is done pro forma makes the violation no less real than when it is done arbitrarily by an autocrat."