This article examines how chance and error were at the root of Carlos Chagas' discovery of the new disease entity that was subsequently named after him. From the perspective of historical epistemology, the author reviews the pathways taken by Chagas' research and raises doubts as to what became the official version, concluding that the logic of history contradicts the right of logic.
Trypanosoma cruzi; Trypanosoma minasense; barbeiro; Chagas' disease