This article has two aims. First, I offer a philological analysis of a key passage from Kant’s Logic: § 6. § 6 is widely regarded as the locus classicus for Kant’s theory of concept formation. However, I show that the part of this section that is most cited and discussed by scholars should not be attributed to Kant, as it is not corroborated by any of his Reflexionen. Second, I attempt to identify Jäsche’s source for this unsupported passage. Ultimately, I conclude that the unsupported passage in § 6 was based on a set of student notes that was similar to the Wiener and Warschauer logic notebooks. However, I also argue that it would be a mistake to regard this passage as the final or definitive statement of Kant’s views about concept formation.