A tariff policy is two-sided and may be compared to a wall. Every export from a country is some other country's import, and every tariff imposition, while apparently a domestic law to bring in a revenue or build up home industries, is, at the same time the means of keeping out some other country's exports. Too often, we look upon only one side of the wall--our own side. We are likely to regard the tariff as a means of controlling the inflow of foreign goods or as a means of raising revenue. But to understand the tariff policy and employ it to its fullest advantage or disadvantage we must be willing and capable of looking over the wall to understand the effect of a tariff--or any other commercial policy--on the aims and aspirations of other nations.