alone belonging to it. The tendency originally was to embrace all of one kindred in one family, and this is the true origin of the gens. But here came in another apparently antagonistic principle. Somehow the lowest races of men realize that close breeding is injurious. How they find it out is an interesting question, but one that cannot be discussed here. They all know it and act upon this knowledge. To preserve the vigor of the race is next in importance to preserving its existence. Therefore marriage institutions must be framed to secure this end as well as the other. Hence the widespread and severe penalties against marrying within the gens. Leaving the vast subject of primitive marriage with these few general hints, we may further note the association of gentes into tribes and the consolidation, by war or otherwise, of tribes into nations. From this to the study of the semi-civilized and civilized nations and governments of the world the steps are easy and natural.
Going back again to the earliest dawn of society we may take up another prominent class of phenomena and study the development of human thought. The simplest phenomena of nature have always been regarded as taking place according to natural laws. The experience of the race and of each individual is sufficient to teach this. Primitive man is not troubled about the causes of the facts of everyday experience, and unbeknown to himself, he reaches the scientific conception of uniformity and invariability in this restricted field. In fact, in a still narrower field, animals also act upon this same principle. If they are not rational they at least are not irrational. What mind qualities they manifest are always thoroughly practical and sane. Their acts are always characterized by what is called "horse sense." It is only rational man who deviates from this norm and indulges in irrational actions. This happens as soon as he begins to reason about phenomena, i. e., to draw inferences from the facts of observation. His data are always at first necessarily insufficient to enable him to draw the correct conclusion, and he consequently draws an erroneous one. When we reflect that it has required ages of exhaustive scientific investigation to enable
