In the hothouse atmosphere of Jena in the last part of the eighteenth century (which Reinhold himself helped to create), Reinhold's star rapidly set about as fast as it rose. Although by 1790 he had become, after Kant, the guiding light of German philosophy, by around 1800 he seems to have been by and large forgotten. It should also be remembered that despite Reinhold's initial and meteoric success, not everybody among the German intellectual public was completely happy with the post-Kantian direction in which he was taking German philosophy. To many, the whole apparatus of “transcendental idealism” itself seemed far-fetched, and, despite Kant's newly won prestige, there were rumblings to be heard against it on all sides of the German intellectual spectrum.

These reached a new crescendo with the publication in 1792 of an anonymous piece chiefly known by the abridgment of its title, “Aenesidemus.” At first the author was anonymous, although his identity was quickly revealed to be that of G. E. L. Schulze, a professor of philosophy at Helmstädt. The literary conceit of the piece involved Schulze's adopting the pseudonym, Aenesidemus (a first-century bc Greek skeptic), who enters into a dialogue with Hermias, a so-called Kantian, so that Aenesidemus–Schulze could demonstrate the bankruptcy of the Kantian position. Offering a self-styled “Humean” attack on Kantianism in general and on Reinhold in particular, “Aenesidemus” proved to be devastating for Reinhold's career.