remarks further, that “all the pottery belonging to the mound-builders’ age, which I have seen, is composed of alluvial clay and sand, or a mixture of the former with pulverized fresh-water shells. A paste made of such a mixture possesses in a high degree the properties of hydraulic Puzzuolani and Portland cement, so that vessels formed of it hardened without being burned, as is customary with modern pottery. The fragments of shells served the purpose of gravel or fragments of stone as at present used in connection with hydraulic lime for the manufacture of artificial stone.”7 The composition of Indian pottery in analogy with that of hydraulic cement suggests the difficulties in the way of inventing the art, and tends also to explain the lateness of its introduction in the course of human experience. Notwithstanding the ingenious suggestion of Prof. Cox, it is probable that pottery was hardened by artificial heat. In some cases the fact is directly attested. Thus Adair, speaking of the Gulf Tribes, remarks that “they make earthern pots of very different sizes, so as to contain from two to ten gallons, large pitchers to carry water, bowls, dishes, platters, basins, and a prodigious number of other vessels of such antiquated forms as would be tedious to describe, and impossible to name. Their method of glazing them is, they place them over a large fire of smoky pitch-pine, which makes them smooth, black and firm.”8

Another advantage of fixing definite ethnical periods is the direction of special investigation to those tribes and nations which afford the best exemplification of each status, with the view of making each both standard and illustrative. Some tribes and families have been left in geographical isolation to work out the problems of progress by original mental effort; and have, consequently, retained their arts and institutions pure and homogeneous; while those of other tribes and nations have been adulterated through external influence. Thus, while Africa was and is an ethnical chaos of savagery and barbarism, Australia and Polynesia were in savagery, pure and simple, with the arts and institutions belonging to that condition. In like manner, the Indian family of America, unlike any other existing family, exemplified the condition of mankind in three successive ethnical periods. In the undisturbed possession of a great continent, of common descent, and with homogeneous institutions, they illustrated, when discovered, each of these conditions, and especially those of the Lower and of the Middle Status of barbarism, more elaborately and completely than any other portion of mankind. The far northern Indians and some of the coast tribes of North and South America were in the Upper Status of savagery; the partially Village Indians east of the Mississippi were in the Lower Status of barbarism, and the Village Indians of North and South America were in the Middle Status. Such an opportunity to recover full and minute information of the course of human experience and progress in developing their arts and institutions through these successive conditions has not been offered within the historical period. It must be added that it has been indifferently improved. Our greatest deficiencies relate to the last period named.

Differences in the culture of the same period in the Eastern and Western hemispheres undoubtedly existed in consequence of the unequal endowments of the continents; but the condition of society in the corresponding status must have been, in the main, substantially similar.

The ancestors of the Grecian, Roman and German tribes passed through the stages we have indicated, in the midst of the last of which the light of history fell upon them. Their differentiation from the undistinguishable mass of barbarians did not occur, probably, earlier than the commencement of the Middle Period of barbarism. The experience of these tribes has been lost, with the exception of so much as is represented by the institutions, inventions and discoveries which they brought with them, and possessed when they first came under historical observation. The Grecian and Latin tribes of the Homeric and Romulian periods afford the highest exemplification of the Upper Status of barbarism. Their institutions were likewise pure and homogeneous, and their experience stands directly connected with the final achievement of civilization.

Commencing, then, with the Australians and Polynesians, following with the American Indian tribes, and concluding with the Roman and Grecian, who afford the highest exemplifications respectively of the six great stages of human progress, the sum of their united experiences may be supposed fairly to represent that of the human family from the Middle Status of savagery to the end of ancient civilization. Consequently, the Aryan nations will find the type of the condition of their remote ancestors, when in savagery, in that of the Australians and Polynesians; when in the Lower Status of barbarism in that of the partially Village Indians of America; and when in the Middle Status in that of the Village Indians, with which their own experience in the Upper Status directly connects. So essentially identical are the arts institutions and mode of life in the same status upon all the continents, that the archaic form of the principal domestic institutions of the Greeks and Romans must even now be sought in the corresponding institutions of the American aborigines, as will be shown in the course of this volume. This fact forms a part of the accumulating evidence tending to show that the principal institutions of mankind have been developed from a few primary germs of thought; and that the course and manner of their development was predetermined, as well as restricted within narrow limits of divergence, by the natural logic of the human mind and the necessary limitations of its powers. Progress has been found to be substantially the same in kind in tribes and nations inhabiting different and even disconnected continents, while in the same status, with deviations from uniformity in particular instances produced by special causes. The argument when extended tends to establish the unity of origin of mankind.

In studying the condition of tribes and nations in these several ethnical periods we are dealing, substantially, with the ancient history and condition of our own remote ancestors.