56 
INTERNATIONAL TRADE 
The answer, as already indicated, depends not so much on the 
existence of non-competing groups in the several countries as on 
the similarity or dissimilarity of their make-up. Their bearing on 
international trade depends on whether they are of the same sort 
or of different sorts in the trading countries. Now, in the occi- 
dental countries — those of advanced civilization in the Western 
world — as a rule the stratification of industrial groups proceeds 
on the same lines. And it is between these countries that the 
principle of comparative costs is presumably of greatest impor- 
tance. Since differences of climatic and physiographic character 
are less wide, divergences of absolute costs are less common and 
less great, and the limits within which the terms of exchange are 
confined not so far apart. And in the Western countries, to 
repeat, we find roughly the same social and industrial layers. The 
unskilled, by far the most numerous, get the lowest wages; the 
mechanics and well-trained stand distinctly higher; and so up- 
ward. This being the case, the differences in money costs between 
the countries are mainly determined by differences in labor costs; 
even tho within each country this factor may be profoundly 
modified. 
Further: that combined influence which domestic and inter- 
national demand may exercise on the position and prosperity of a 
given non-competing group is not of so great importance in prac- 
tice as it is for the completeness and consistency of theoretic 
analysis. It is less important because the demand from abroad 
for any set of commodities, and thereby for the services of a par- 
ticular grade of labor applied to making those commodities, is 
rarely so dominant as to change those relations between grades 
which would obtain within the country in any case. The lines of 
social and industrial stratification in a country are determined 
chiefly by the conditions that prevail within its own limits — by 
the numbers in the several groups and their demands for each 
others’ services, and in some uncertain degree by their different 
standards of living. An added impact of demand from a foreign 
country will rarely change the relative rates of wages which have 
come about from the domestic factors. The social stratification