As has been remarked above, in the course of time and change the advance of the industrial arts and of the institutions of ownership have taken such a turn that the working system of industry and business no longer runs on national lines and, indeed, no longer takes account of national frontiers,--except in so far as the national policies and legislation, arbitrarily and partially, impose these frontiers on the workings of trade and industry. The effect of such regulation for political ends is, with wholly negligible exceptions, detrimental to the efficient working of the industrial system under modern conditions; and it is therefore detrimental to the material interests of the common citizen. But the case is not the same as regards the interests of the traders. Trade is a competitive affair, and it is to the advantage of the traders engaged in any given line of business to extend their own markets and to exclude competing traders. Competition may be the soul of trade, but monopoly is necessarily the aim of every trader. And the national organisation is of service to its traders in so far as it shelters them, wholly or partly, from the competition of traders of other nationalities, or in so far as it furthers their enterprise by subvention or similar privileges as against their competitors, whether at home or abroad. The gain that so comes to the nation's traders from any preferential advantage afforded them by national regulations, or from any discrimination against traders of foreign nationality, goes to the traders as private gain. It is of no benefit to any of their compatriots; since there is no community of usufruct that touches these gains of the traders. So far as concerns his material advantage, it is an idle matter to the common citizen whether he deals with traders of his own nationality or with aliens; both alike will aim to buy cheap and sell dear, and will charge him "what the traffic will bear." Nor does it matter to him whether the gains of this trade go to aliens or to his compatriots; in either case equally they immediately pass beyond his reach, and are equally removed from any touch of joint interest on his part. Being private property, under modern law and custom he has no use of them, whether a national frontier does or does not intervene between his domicile and that of their owner.