Shamanism, Sorcerers and Spirit Seers – by Dr. Arnoldo Krumm-Heller in 1946 is a previously unpublished historical record that explores the nature and work of Sorcerers, Shamanic Healers, and Medicine men of Mexican and South American Indians in relation to world medicine in the 1900s. Dr Krumm-Heller records 40 years of research travelling through Colombia, Ecuador, Chile, Peru, Mexico, Argentina, France, Germany, and Spain, into complementary medicines of the indigenous Mapuches, Incas, Mayas, and Aztecs. 
A Shaman is a very specific type of healer who uses an alternate state of consciousness to enter the invisible world, which is made up of all unseen aspects of the world that affect us, including the spiritual, emotional, mental, mythical, archetypal, and dream worlds.

A Sorcerer is a user of magic who relies on willpower, experience, and instinct.

A Spirit Seer is someone who is able to prophesize future events. They are endowed with profound moral and spiritual insight or knowledge, and possesses highly intuitive abilities and supernatural sight.