In Bell's Gap Railroad Co. v. Pennsylvania, 134 U.S. 232 (1890), it was decided that under the power of classification there might be exemption of property dependent upon its species and the rates of excise might be varied upon different trades and products. And it was said that it was safe to say "that the Fourteenth Amendment was not intended to compel the State to adopt an iron rule of equal taxation." It was pointed out that to give it that effect would destroy the constitutional provision and laws of some of the States which, while enjoining uniformity of taxation, permitted exceptions which were deemed material, and that "it would render nugatory those discriminations which the best interests of society require; which are necessary for the encouragement of needed and useful industries, and the discouragement of intemperance and vice; and which every State, in one form or another, deems it expedient to adopt." The Court held: "The provision in the Fourteenth Amendment, that no State shall deny to any person within its jurisdiction the equal protection of the laws, was not intended to prevent a State from adjusting its system of taxation in all proper and reasonable ways. It may, if it chooses, exempt certain classes of property from any taxation at all, such as churches, libraries and the property of charitable institutions. It may impose different specific taxes upon different trades and professions, and may vary the rates of excise upon various products; it may tax real estate and personal property in a different manner; it may tax visible property only, and not tax securities for payment of money; it may allow deductions for indebtedness, or not allow them. All such regulations, and those of like character, so long as they proceed within reasonable limits and general usage, are within the discretion of the state legislature, or the people of the State in framing their constitution. But clear and hostile discriminations against particular persons and classes, especially such as are of an unusual character, unknown to the practice of our governments, might be obnoxious to the constitutional prohibition. It would, however, be impracticable and unwise to attempt to lay down any general rule or definition on the subject that would include all cases."