The general similarity of the Aztec confederacy to that of the Iroquois, in point of social structure, is thus clearly manifest. Along with this general similarity we have observed some points of higher development, such as one might expect to find in traversing the entire length of an ethnical period. Instead of stockaded villages, with houses of bark or of clay supported upon a wooden framework, we have pueblos of adobe-brick or stone, in various stages of evolution, the most advanced of which present the appearance of castellated cities. Along with the systematic irrigation and increased dependence upon horticulture, we find evidences of greater density of population; and we see in the victorious confederacy a more highly developed organization for adding to its stock of food and other desirable possessions by the systematic plunder of neighbouring weaker communities. Naturally such increase in numbers and organization entails some increase in the number of officers and some differentiation of their functions, as illustrated in the representation of the clans (_calpulli_) in the tribal council (_tlatocan_), by speakers (_tlatoani_) chosen for the purpose, and not by the official heads (_calpullec_) of the clan. Likewise in the military commander-in-chief (_tlacatecuhtli_) we observe a marked increase in dignity, and--as I have already suggested and hope to maintain--we find that his office has been clothed with sacerdotal powers, and has thus taken a decided step toward kingship of the ancient type, as depicted in the Homeric poems. [Sidenote: Aztec priesthood: human sacrifices.] No feature of the advance is more noteworthy than the development of the medicine-men into an organized priesthood.[128] The presence of this priesthood and its ritual was proclaimed to the eyes of the traveller in ancient Mexico by the numerous tall truncated pyramids (_teocallis_), on the flat summits of which men, women, and children were sacrificed to the gods. This custom of human sacrifice seems to have been a characteristic of the middle period of barbarism, and to have survived, with diminishing frequency, into the upper period. There are abundant traces of its existence throughout the early Aryan world, from Britain to Hindustan, as well as among the ancient Hebrews and their kindred.[129] But among all these peoples, at the earliest times at which we can study them with trustworthy records, we find the custom of human sacrifice in an advanced stage of decline, and generally no longer accompanied by the custom of cannibalism in which it probably originated.[130] Among the Mexicans, however, when they were first visited by the Spaniards, cannibalism flourished as nowhere else in the world except perhaps in Fiji, and human sacrifices were conducted on such a scale as could not have been witnessed in Europe without going back more than forty centuries.