For the sciences that deal with the psychology of human conduct a similarly searching analysis of the elementary facts of behaviour is doubtless similarly desirable; and under such closer scrutiny of these facts it will doubtless appear that here, too, the broad term “instinct” is of too unprecise a character to serve the needs of an exhaustive psychological analysis. But the needs of an inquiry into the nature and causes of the growth of institutions are not precisely the same as those of such an exhaustive psychological analysis. A genetic inquiry into institutions will address itself to the growth of habits and conventions, as conditioned by the material environment and by the innate and persistent propensities of human nature; and for these propensities, as they take effect in the give and take of cultural growth, no better designation than the time-worn “instinct” is available. In the light of recent inquiries and speculations it is scarcely to be questioned that each of these distinguishable propensities may be analysed into simpler constituent elements, of a quasi-tropismatic or physiological nature;[1] but in the light of every-day experience and common notoriety it is at the same time not to be questioned that these simple and irreducible psychological elements of human behaviour fall into composite functional groups, and so make up specific and determinate propensities, proclivities, aptitudes that are, within the purview of the social sciences, to be handled as irreducible traits of human nature. Indeed, it would appear that it is in the particular grouping and concatenation of these ultimate psychological elements into characteristic lines of interest and propensity that the nature of man is finally to be distinguished from that of the lower animals.