According to him, then, there was no kingdom or empire of Mexico. There was simply a confederacy of three tribes, and this confederacy was a military democracy. The governmental powers were vested in a council of chiefs with a general commander. The council exercised all civil power, the military power being left in the hands of the war chief. There were no feudal castles inhabited by lawless lords. There were only great communal houses tenanted by clans. In his brilliant work on Ancient Society, Mr. Morgan places below civilization two stages of development--savagery and barbarism. The invention of pottery marks the difference between these two stages. The savage makes no pottery. When the women of the savage tribes used vessels of fire-hardened clay for boiling their food they had passed into the first stage of barbarism. Elsewhere there were pastoral stages of development. In North America there were none. The only domesticated animal its inhabitants possessed when the Europeans landed on the continent was the dog. The first stage of barbarism in North America was marked by the cultivation of maize or Indian corn. This grain can be cultivated more easily than any other cereal. No other yields such enormous returns. In virgin soil it is only necessary to drop the seed into the earth. Nature cares for its complete development. But virgin soil becomes exhausted in a few years. As population becomes denser and migrations cease to be practicable, the land must be more carefully tilled, and, where rains are comparatively infrequent, must be irrigated. Irrigation and the use of adobe (sun-dried brick) and stone in building mark the beginning of the second period of barbarism. In this period also tools of stone give place to those of metal, the metal used in America being copper. The Aztecs, the Mayas, and, in South America, the Peruvians were in the second period. But to the third period, when the smelting of iron ore was invented, these people never passed.