  Though little known in the Anglophone world, and largely forgotten even in the Germanic world, August Wilhelm Rehberg (1757-1836) was a pivotal thinker in the era of classical German philosophy from Kant to Hegel.  No thinker from that fertile period has been more unjustly neglected.  He wrote some acute and highly-regarded reviews of Kant, and he corresponded with Kant about the philosophy of  mathematics.[1]  Kant's reply to Rehberg's objections is one of his most important explanations of his mathematical  doctrines.[2]  Such, indeed, was Rehberg's grasp of Kant that J.B. Jachmann, Kant's friend and biographer, regarded him as “the finest head among all your  students.”[3]  But Rehberg was much more than a Kantian epigone.  He also made an original contribution to the pantheism controversy, where he staked out his own position vis-à-vis Jacobi, Mendelssohn, Herder and Kant; and he wrote an influential critique of Reinhold's Elementarphilosophie, which was a potent source of the skepticism surrounding neo-Kantian foundationalism in the early 1790s. All these facts are sufficient to give Rehberg a notable, if minor, place in the intellectual pantheon of his age.  They are not, however, the main reason for remembering him.  