1. Lower Stage. Dates from the introduction of the art of pottery. The latter is traceable in many cases, and probably attributable in all cases, to the custom of covering wooden or plaited vessels with clay in order to render them fire-proof. It did not take long to find out that moulded clay served the same purpose without a lining of other material. Hitherto we could consider the course of evolution as being equally characteristic, in a general way, for all the nations of a certain period, without reference to locality. But with the beginning of barbarism, we reach a stage where the difference in the natural resources of the two great bodies of land makes itself felt. The salient features of this stage of barbarism is the taming and raising of animals and the cultivation of plants. Now the eastern body of land, the so-called old world, contained nearly all the tamable animals and all the cultivable species of grain but one; while the western continent, America, possessed only one tamable mammal, the llama (even this only in a certain part of the South), and only one, although the best, species of grain: the corn. From now on, these different conditions of nature lead the population of each hemisphere along divergent roads, and the landmarks on the boundaries of the various stages differ in both cases. 2. Middle Stage. Commencing in the East with the domestication of animals, in the West with the cultivation and irrigation of foodplants; also with the use of adobes (bricks baked in the sun) and stones for buildings. We begin in the West, because there this stage was never outgrown up to the time of the conquest by Europeans. At the time of their discovery, the Indians in the lower stage of barbarism (all those living east of the Mississippi) carried on cultivation on a small scale in gardens. Corn, and perhaps also pumpkins, melons and other garden truck were raised. A very essential part of their sustenance was produced in this manner. They lived in wooden houses, in fortified villages. The tribes of the Northwest, especially those of the region along the Columbia river, were still in the higher stage of savagery, ignorant of pottery and of any cultivation of plants whatever. But the so-called Pueblo Indians in New Mexico, the Mexicans, Central-Americans and Peruvians, were in the middle-stage of barbarism. They lived in fortlike houses of adobe or stone, cultivated corn and other plants suitable to various conditions of localities and climate in artificially irrigated gardens that represented the main source of nourishment, and even kept a few tamed animals--the Mexicans the turkey and other birds, the Peruvians the llama. Furthermore they were familiar with the use of metals--iron excepted, and for this reason they could not get along yet without stone weapons and stone implements. The conquest by the Spaniards cut short all further independent development.