In general the causes of our recent and present immigration may be divided into two classes, the natural and the artificial. Most of what has been said thus far refers to the former; the latter has been merely hinted at. Another distinction which is often helpful is that between the permanent or predisposing causes, and the temporary or immediate causes. It frequently happens that in a given country there are conditions of long standing—perhaps inherent in the character of the country itself—which make life hard and disagreeable for the resident. Yet no immigration takes place until some relatively trivial event, of a temporary nature, occurs, which serves as the final impulse to emigration. To the superficial view this temporary event appears as the cause of emigration, when in point of fact its weight in the total amount of dissatisfactions is insignificant.[121] The natural causes of immigration at the present time lie primarily in the superiority of the economic conditions in the United States over those in the countries from which the immigrants come. Modern immigration is essentially an economic phenomenon. Religious and political causes have played the leading part in the past, and still enter in as contributory factors in many cases. But the one prevailing reason why the immigrant of to-day leaves his native village is that he is dissatisfied with his economic lot, as compared with what it might be in the new world. The European peasant comes to America because he can—or believes he can—secure a greater return in material welfare for the amount of labor expended in this country than in his home land. This fact is recognized by practically all careful students of the subject, and is frequently emphasized in the recent report of the Immigration Commission. It is worthy of notice, also, that the changes which affect the volume of the immigration current, and cause those repeated fluctuations which we have observed, are changes in the economic situation in this country, rather than in the countries of source. A period of good times in this country attracts large numbers of immigrants by promising large rewards for labor; an industrial depression checks the incoming current, and sends away many of those who are here. This is probably accounted for by the fact that economic conditions in this country are subject to greater oscillations than in European countries which are relatively static, rather than dynamic. An example of the opposite condition is furnished by the Irish emigration of the middle of the nineteenth century, when a great economic disaster in the country of source occasioned a large increase in emigration. This relation between the economic situation in this country and the volume of immigration has been worked out statistically by Professor Commons, and is presented in graphic form in a table in his book, _Races and Immigrants in America_ (opposite page 64). In this table he takes imports as an index of the prosperity of the