Whatever there is in nature which the Indian cannot grasp at once, he attributes to mysterious supernatural agencies.  He believes that nature is pervaded by spiritual essence individualized into an infinite number of distinct powers.  Everything in nature has a soul according to him, and it is that soul which causes it to move or to act upon its surroundings in general.  Thus the medical properties of animals, of plants, or minerals, are due to spiritual manifestations.  His medical art therefore does not consist merely in eliminating the physical cause of disease.  As soon as any disease is stubborn there must be at the bottom of it some spiritual source, and this source can be discovered and removed only by magic.

Incantations therefore form an important part of Indian medicine.  The formulas therefor are the special property of the medicine-men, whom we shall hereafter designate with the much more appropriate name of Shamans.  The shaman is wizard and physician at the same time.  He is also a prophet, augur, and oracle.  His duty it is not only to protect from evil, but to counteract it.  He has charms and incantations which he offers for the production of beneficial natural phenomena.

Magic for such purposes is regarded by the Indian as essential to the existence of man.  Magic, however, as a black art is the most heinous crime which he can conceive.  The difference between the two consists mainly in their purpose; the manipulations are substantially the same, so are the objects.  To know those details is one of the attributes of the shamans.

The latter constitute a circle of their own,—­a cluster of adepts, nominally in the arts of healing, but really in the arts of magic.  That circle is wide, and whoever stands outside of it has no right to infringe upon the duties of its members by attempting to follow their example.  It is an institution, and its origin dates from untold centuries.  It is subdivided into groups, each of which practises charms, incantations, or magic, relating to certain human interests.  The Shyayak are in possession of the spell which charms game, in other words they are the shamans of the hunt.  The Uakanyi practise magic in warfare, they are the shamans of war.  The Chayani are physicians who combine with the knowledge of medicine proper, the knowledge of magic curative powers.  They are the shamans of medicine.  Lastly the Yaya combine a knowledge of all these different branches in their essence.  They are the prophets and priests.  These groups may be described as, in a certain sense, guilds.  But they are secret societies also, inasmuch as the arts and practices of each are special property which is kept secret from the others, and from the uninitiated members in the tribe.  In order to become a member of a society of that kind secrecy is required and long apprenticeship.  The novice rises slowly from one degree of knowledge to another, and only few attain the higher positions.