Classification is less easy to defend from the standpoint of the traffic manager alone, than from that of the vice-president in charge of operation. Value of service is at times difficult to understand. It is not at first sight reasonable, that of two commodities which cost the railway exactly the same amount to transport, one should be charged twice as much as the other. For example, the rate on anthracite coal is very much higher than upon soft coal; the rate upon wheat is higher than the rate upon some other foodstuffs; the rate upon fine woollen goods is very much higher than upon coarse cotton cloth, etc.[338] It has been urged frequently that any discrimination in the freight rate on the basis of difference, either in the value of the commodity itself or in the value of the service rendered, is unreasonable and unjust. The case, however, is entirely analogous to that of discrimination between a long and short haul of the same goods. The principle is perfectly defensible in both cases, and has been accepted in legal decisions as well as by economic writers for many years. It is based upon the fact, which confronts one at every turn in a discussion of railway economics, that a large proportion of the expenses of a railway is independent of the amount of traffic. These fixed expenses must be met at all cost if the road is to remain solvent. They constitute a charge upon the entire traffic of the line, and are not susceptible of apportionment to each unit of transportation. Any rate which will contribute a surplus, small or large, above the mere cost of transportation,--that is to say, above the expenses incident to this particular carriage,--and which thereby lessens by the amount of that excess the burden of the fixed charges remaining upon other traffic, is justifiable. But it is defensible only under two conditions. The first is that the goods at any higher rate will go by another route or not at all; and the second is that the effect may not be detrimental to the general course of business,--that is to say, that it is not opposed to the public welfare. Thus a long haul at a lower rate than the rate charged for a shorter haul, if it must be lower in order to secure the business, constitutes no injustice to the local shipper; for the surplus remaining above the cost of haulage of that particular increment of freight lessens thereby the charge which must be made upon local freight for meeting interest on bonds, maintenance of way, and equipment expenses, etc., all of which charges, as we have seen, go on more or less independently of the traffic. On precisely the same grounds a discrimination of freight rates in favor of the cheaper commodity or the less valuable service may be defended. Coal or sand may reasonably be carried at two and one-fourth mills per ton mile, while the road is coincidently charging three or four times as much for hauling dry goods or fine hardware. For if a quarter of a mill