While there have always been schools of religious and ethical thought favourable to poverty, or a simple life, the general opinion of mankind has always regarded the increasing wealth of an individual or a community as conducive to human happiness. Qualifications have commonly been attached to this judgment in recognition of a certain danger and deceitfulness of riches, especially when rapidly acquired and lavishly expended, but the presumption still stands that wealth in general conduces to well-being. The nature, degree or conditions of this correspondence have, however, received singularly little attention from those thinkers who have given closest study to economic processes. Many of the founders of economic science in this and other countries were manifestly concerned for the general welfare of their fellowmen, and were active workers in many fields of social reform. But, in formulating the concepts and laws of their science, they deemed it unnecessary to give any close or continuous thought to the relations between economic wealth and human welfare. This was due, partly, no doubt to the natural desire to make the subject-matter and the treatment of a new science as definitely concrete and measurable as possible. It was this desire that made monetary valuation paramount in all economic estimates.