The works of Karl Leonhard Reinhold (1757-1823) were a major factor in the development of post-Kantian philosophy, yet his exact contribution is still under discussion. This book investigates how Reinhold s background in Enlightenment influenced his reception of Kant s critical philosophy. From his pre-Kantian efforts up to the point where he began distancing himself from the master, Reinhold s own philosophical development takes center stage. This development, rather than critical philosophy, was the main ingredient of Reinhold s contribution to post-Kantian philosophy.