In so far as modern science inquires into the phenomena of life, whether inanimate, brute, or human, it is occupied about questions of genesis and cumulative change, and it converges upon a theoretical formulation in the shape of a life-history drawn in causal terms. In so far as it is a science in the current sense of the term, any science, such as economics, which has to do with human conduct, becomes a genetic inquiry into the human scheme of life; and where, as in economics, the subject of inquiry is the conduct of man in his dealings with the material means of life, the science is necessarily an inquiry into the life-history of material civilization, on a more or less extended or restricted plan. Not that the economist's inquiry isolates material civilization from all other phases and bearings of human culture, and so studies the motions of an abstractly conceived "economic man." On the contrary, no theoretical inquiry into this material civilization that shall be at all adequate to any scientific purpose can be carried out without taking this material civilization in its causal, that is to say, its genetic, relations to other phases and bearings of the cultural complex; without studying it as it is wrought upon by other lines of cultural growth and as working its effects in these other lines. But in so far as the inquiry is economic science, specifically, the attention will converge upon the scheme of material life and will take in other phases of civilization only in their correlation with the scheme of material civilization. Like all human culture this material civilization is a scheme of institutions--institutional fabric and institutional growth. But institutions are an outgrowth of habit. The growth of culture is a cumulative sequence of habituation, and the ways and means of it are the habitual response of human nature to exigencies that vary incontinently, cumulatively, but with something of a consistent sequence in the cumulative variations that so go forward,--incontinently, because each new move creates a new situation which induces a further new variation in the habitual manner of response; cumulatively, because each new situation is a variation of what has gone before it and embodies as causal factors all that has been effected by what went before; consistently, because the underlying traits of human nature (propensities, aptitudes, and what not) by force of which the response takes place, and on the ground of which the habituation takes effect, remain substantially unchanged.