The practice of medicine by the shamans is an invocation to the gods to drive out evil spirits from the sick and to frighten them that they may leave. By music and dancing they obtain the help of the ancients, and by a great variety of methods they drive out the evil beings. Resort is often had to scarifying and searing, especially when the sick man has great local pains. All American tribes entertain a profound belief in the doctrine of signatures,--_similia, similibus curantur_,--and they use this belief in procuring charms as medicine to drive out the ghostly diseases that plague their sick folk.
Next in importance to terpsichorean worship is altar worship. The altar is a space cleared upon the ground, or a platform raised from the ground or floor of the kiva or assembly-house of the people. Around the altar are gathered the priests and their acolytes, and here they make prayers and perform ceremonies with the aid of altar-pieces of various kinds, especially tablets of picture-writings on wood, bone, or the skins of animals. The altar-pieces consist of representatives of the thing for which supplication is made: ears of corn or vases of meal, ewers of water, parts of animals designed for food, cakes of grasshoppers, basins of honey, in fine any kind of food; then crystals or fragments of rock to signify that they desire the corn to be hard, or of honeydew that they desire the corn to be sweet, or of corn of different colors that they desire the corn to be of a variety of colors. That which is of great interest to students of ethnology is the system of picture-writing exhibited on the altars. In this a great variety of things which they desire and a great variety of the characteristics of these things are represented in pictographs, or modeled in clay, or carved from wood and bone. The graphic art, as painting and sculpture, has its origin with tribal men in the development of altar-pieces. So also the drama is derived from primeval worship, as the modern practice of medicine has been evolved from necromancy.
There is another method of worship found in savagery, but more highly developed in barbarism,--the worship of sacrifice. The altar-pieces and the dramatic supplications of the lower stage gradually develop into a sacrificial stage in the higher culture. Then the objects are supposed to supply the ancients themselves with food and drink and the pleasures of life. This stage was most highly developed in Mexico, especially by the Nahua or Aztec, where human beings were sacrificed. In general, among the Amerinds, not only are sacrifices made on the altar, but they are also made whenever food or drink is used. Thus the first portions of objects designed for consumption are dedicated to the gods. There are in America many examples of these pagan religions, to a greater or less extent affiliated in doctrine and in worship with the religion of Christian origin.