An unrecognised copy (1665) in Kant’s private library of Michael Piccart’s Isagoge (1605), an introduction to the system of Aristotelian philosophy together with Kant’s own remarks on this author (Refl 4160, AA 17, p. 439) can be established as an original source for the Kantian ‘ideosphere’. First, I point out contexts and consequences of Piccart’s Altdorfian Aristotelianism, in contrast to the Königsbergian Aristotelianism (emphasised by Tonelli’s research). To further check the quality of Piccart as a source of Kant’s, a conceptual (...) case-study is elaborated with Kant’s critical distinction between analytics as a “logic of truth” (KrV, B 85) and dialectics as a “logic of illusion” (KrV, B 86). Hereby, dialectics is understood as part of an Aristotelian division of logic in analytics, dialectics and sophistics (Königsberg/Rabe versus Altdorf/Piccart). As will be shown by the paradigmatic case of the famous Königsbergian proponent of Aristotelianism, Paul Rabe, Kant cannot have received the suggestion for his own critical distinction from Rabe’s Cursus Philosophicus. Instead, Piccart refers to a passage of Aristotle’s Metaphysics, which suggests the very distinction between an analytic philosopher who searches for scientific truth and dialecticians and sophists. For different reasons, they do not claim any scientific seriousness. (shrink)