That there is a common cause, an that it is either what we call material progress or something closely connected with material progress, becomes more than an inference when it is noted that the phenomena we class together and speak of as industrial depression are but intensifications of phenomena which always accompany material progress, and which show themselves more clearly and strongly as material progress goes on. Where the conditions to which material progress everywhere tends are the most fully realized—that is to say, where population is densest, wealth greatest, and the machinery of production and exchange most highly developed — we find the deepest poverty, the sharpest struggle for existence, and the most of enforced idleness.

Introductory : The Problem. - Progress and Poverty (1879)