This paper introduces and reproduces a document from Feyerabend’s Nachlass including: (i) Feyerabend’s 1967 tentative translation into English of an original German typescript reporting the lecture notes of an academic course on magnetic monopoles delivered by physicist Felix Ehrenhaft (1879-1952) at the University of Vienna in the 1947 summer semester; and (ii) Feyerabend’s memoir focusing on Ehrenhaft in postwar Vienna.In addition to making available to a larger audience Ehrenhaft’s lectures on a highly controversial topic, the publication of Feyerabend’s typescript offers (...) the opportunity to reconsider, delve deeper into and cast a brighter light on a rather neglected aspect in the growing literature on Feyerabend’s thought: the significance of Ehrenhaft for the development of Feyerabend’s intellectual biography. (shrink)