Shamanism, the supposed individual control of the supernatural through a personally acquired power of communication with the spirit world, rests upon much the same basis in California as elsewhere in North America. In general among uncivilized tribes the simpler the stage of culture the more important the shaman. It is as if he constituted an element that remained nearly constant in quantity of effect, as it is fundamentally unvarying in form, through all successive periods of civilization to the highest; but that as increase in degree of civilization brought with it ever more and more new elements, religious and otherwise, and these unfolded in ever expanding complexity, he became, relatively to the total mass of thought and action of a people, less and less important. Certainly the difference is marked between the Eskimo, whose religion consists of little else than shamanism, and the much more highly organized Indians of the North Pacific Coast, where shamanism is but one of several and by no means the most important religious factor, even though it may be the most deep seated. The same contrast is found between the rude simple-minded Indians of California as compared with those of the Plains and of the Southwest, where the supremacy of the shaman is rather obscured by that of the priest conversant with a ceremony. Even within California the difference holds good. In the Northwest, where the native civilization reached on the whole its greatest complexity, the shaman is less prominent than anywhere else in the state. In the south, where the culture is also more developed than in the Central part of the state, the shaman is certainly as much dreaded as there; but that his province is more restricted is shown by the fact that in Southern California the shamans in their capacity as such do not seem to form associations, perform public ceremonies, or directly participate in the tribal dances.

The power of the shaman being directly dependent upon his personal acquisition of a connection with the supernatural world, an understanding of the method by which this acquisition takes place generally furnishes also a pretty accurate idea of the nature of his functions and influence. The most common way of acquiring shamanistic power in California, as in so many other parts of the world, is by dreaming. A spirit, be it that of an animal, a place, the sun or another natural object, a deceased relative, or an entirely unimbodied spirit, visits the future medicine-man in his dreams, and the connection thus established between them is the source and basis of the latter's power. This spirit becomes his guardian spirit or "personal." From it he receives the song or rite or knowledge of the charm and the understanding which enable him to cause or remove disease and to do and endure what other men cannot. In California, with a few special exceptions, the idea does not seem so prevalent as elsewhere that this guardian spirit is an animal. Occasionally it is the ghost of a person who has once lived, usually a relative. Perhaps most frequently it is merely a spirit as such, not connected with any tangible embodiment or form, either human, animate, or inanimate. The belief that the shaman acquires the spirits most frequently in dreaming is prevalent through the whole Sierra Nevada region and in many other parts of the state.

In certain regions another important method, that of the waking vision and trance, is recognized. The person is in a wild desolate place, perhaps hunting. Suddenly there is an appearance before him. He becomes unconscious and while in this state receives his supernatural power. On his return to his people he is for a time demented or physically affected. After he again becomes normal he has control of his supernatural influences. Such beliefs prevail in part among the Yuki and Athabascans of the Coast Range and the Maidu of the Sacramento valley, and no doubt occur more or less sporadically in other regions.

Finally, the shaman sometimes acquires his powers through seeking for them rather than by having them thrust upon him during a dream or vision. This of course is a common procedure in the Plains and in part on the North Pacific Coast. Among the Yurok of the lower Klamath, for instance, the person whom the spirits have visited in dreams, ascends high peaks where he spends one or more nights until he has acquired his powers. Among the Wiyot of Humboldt Bay there are similar beliefs. In the same Northwestern region a man who wishes to be fierce, strong, and invulnerable swims at night in lakes inhabited by monsters or thunders. From these, if his courage is sufficient to await and endure their presence, he receives the desired powers. This practice of bathing in lonely lakes closely recalls the custom prevalent along the Pacific slope for some distance northward, and within California it is probably not strictly confined to the Northwestern culture area. On the whole, however, this deliberate method of acquiring shamanistic power is not common, nor, as has already been stated, would it be in accord with the generally lower intensity of religious feeling among the California Indians as compared with those of most other parts of the continent.

The Northwestern area is not only exceptional in being the principal one within the state where this deliberate seeking of shamanistic power is prevalent. The conception of a guardian spirit is much less clearly defined among the Northwestern tribes, with whom the possession of "pains," the small material objects which cause disease, rather than of true spirits, seems to be what is generally associated with shamanistic power. As already stated, shamanism forms a much less important part of religion as a whole in the Northwestern area than elsewhere, and it is in accord with this fact that the majority of the shamans, and those supposed to be most powerful, are women.

In parts of Southern California also the idea of the guardian spirit does not seem to be well developed. Here the method of acquiring shamanistic power is almost exclusively by dreams; but among the Mohave and probably other Colorado river tribes, myths, and not a personal meeting or communion with an individual spirit, constitute the subject of the dreams. The Mohave shamans believe that they were present at the beginning of the world, before mankind had separated into tribes. They were with the great leader and almost creator, Mastamho. They saw him singing, blowing, and rubbing over the body of a sick man, if their own power be that of curing disease, and from Mastamho they thus learned the actions and speeches which constitute their power. Before him they showed what they had learned from him, and by him were designated those who had seen and learned most and those of less power. Each man saw only the shamanistic actions relating to his particular power, whether these had reference to the curing of disease, to love, to war, or to some other activity. The Mohave universally speak of having dreamed these scenes, just as each narrator affirms his knowledge of non-shamanistic myths and of ceremonies to have been individually derived from dreaming them. It is probable that to a certain extent this is true. That it is not entirely true becomes evident when the Mohave with equal unanimity state that these dreams were dreamed by them before birth. In other words, their statement that they have dreamed such experiences is to be interpreted mainly as a belief that they as individuals were present in spirit form at the beginning of the world, at the time when it took shape and everything was ordained, and when all power, shamanistic and otherwise, was established and allotted. It is obvious that with this conception as the basis of their whole religion, there is but little room for any beliefs as to guardian spirits of the usual form.

Of course there is nothing that limits the shaman to one spirit, and among many or most tribes, such as the Maidu, a powerful medicine-man may possess a great number.

Frequently in Central and Northwestern California there is some more or less public ceremony at which a new shaman is, so to speak, initiated before he practices his powers. The body of initiated shamans do not form a definite society or association. The ceremony is rather an occasion that marks the first public appearance of the novice, in which he receives for his own good, and presumably for that of the community also, the assistance of the more experienced persons of his profession. Commonly it is thought that the novice cannot receive and exercise the full use of his powers without this assistance. The ceremony is usually held in the ceremonial chamber and is accompanied by dancing. The efforts of the older shamans are directed toward giving the initiate a firm and permanent control of the spirits which have only half attached themselves to him and which are thought to be still more or less rebellious. Of course exhibitions of magic and of the physical effects of the presence of the spirits are a prominent feature of these ceremonies. This initiation of doctors is found among the Northwestern tribes and in the Central region among the Maidu and Wintun and probably other groups.

A special class of shamans found to a greater or less extent among probably all the Central tribes, though they are wanting both in the Northwest and the South, are the so-called bear doctors, shamans who have received power from grizzly bears, often by being taken into the abode of these animals—which appear there in human form,—and who after their return to mankind possess many of the qualities of the grizzly bear, especially his apparent invulnerability to fatal attack. The bear shamans can not only assume the form of bears, as they do in order to inflict vengeance on their enemies, but it is believed that they can be killed an indefinite number of times when in this form and each time return to life. In some regions, as among the Pomo and Yuki, the bear shaman was not thought as elsewhere to actually become a bear, but to remain a man who clothed himself in the skin of a bear to his complete disguisement, and by his malevolence, rapidity, fierceness, and resistance to wounds to be capable of inflicting greater injury than a true bear. Whether any bear shamans actually attempted to disguise themselves in this way to accomplish their ends is doubtful. It is certain that all the members of some tribes believed it to be in their power.

The rattlesnake doctor, who cured or prevented the bite of the rattlesnake, was usually distinct from other medicine-men. Among the Yuki his power, as that of the rattlesnake, was associated with the sun; among the Maidu with the thunder. Among the Yokuts the rattlesnake shamans annually held a public ceremony designed to prevent rattlesnake bites among the tribe. On this occasion they displayed their power over the snakes by handling them in a manner analogous to that of the Hopi, and by even allowing themselves to be bitten.