such a basis attention is next asked to the following line of investigations. It is essential at the outset to correct reasoning that the distinction between _taxation_ and _spoliation_ be kept clearly in view. That only is entitled to be called a tax law which levies uniformly upon all the subjects of taxation; which does not of itself exempt any part of the property of _the same_ class which is selected to bear the primary burden of taxation, or by its imperfections to any extent permits such exemptions. All levies or assessments made by the State on the persons, property, or business of its citizens that do not conform to such conditions are spoliations, concerning which nothing but irregularity can be predicated; nothing positive concerning their diffusion can be asserted; and the most complete collection of experiences in respect to them can not be properly dignified as "a science." And it may be properly claimed that from a nonrecognition or lack of appreciation of the broad distinction between taxation and spoliation, the disagreement among economists respecting the diffusion of taxes has mainly originated. With this premise, let us next consider what facts and experiences are pertinent to this subject, and available to assist in reaching sound conclusions; proceeding very carefully and cautiously in so doing, inasmuch as territory is to be entered upon that has not been generally or thoroughly explored. The facts and experiences of first importance in such inquiry are that the examination of the tax rolls in any State, city, or municipality of the United States will show that surprisingly small numbers of persons primarily pay or advance any kind of taxes. It is not probable that more than one tenth of the adult population or about one twentieth of the entire population of the United States ever come in contact officially with a tax assessor or tax collector. It is also estimated that less than two per cent of the total population of the United States advance the entire customs and internal revenue of the Federal Government.