By using material coining from a northwest Amazon society, the Tatuyo of Pirâ-Paranâ, the author envisages the shaman as a "doer" whose tool is thought, and its correlate knowledge, the product of his activity. In the Tatuyo society, the shaman is, in effect, designated by the term "he who knows" — according to a nominal construction that is identical to the one used to particularize the sun as being "he who heats"— and his work essentially consists in filling with thought the "blank" spaces situated between things and inside things : this situation corresponds to his proper name of kumu formed out of the word "bench", kumuno, from which has been taken away a particle, no, being used to materialize things in the same way that nâû means "cassava pancake" whereas nâïïnô designates the cassava pancake set there to be eaten.