  Rehberg's early interests were in philosophy and literature rather than politics.  Intellectually precocious, he learned to read Greek, Latin, Italian, Spanish, French and English before he was fifteen. From 1774 to 1777 he attended the University of Göttingen, then one of the main centers of intellectual life in Germany.  Finding little inspiration from the Popularphilosophie then prevalent in Göttingen, Rehberg resolved to educate himself, and did so by studying Leibniz and Spinoza on his own.  One hallmark of Rehberg's intellectual character—central for his philosophy and politics—was his skepticism, which he formed in his earliest years.  When he was only fourteen, he had doubts about Christianity, and soon became an unbeliever, which he remained for the rest of his life.  His skepticism soon extended to metaphysics itself.  He had his doubts about Leibniz and Spinoza, because their systems rested upon questionable and indemonstrable first principles.  In 1779 he wrote an essay for a competition organized by the Berlin Academy, where he took a skeptical position regarding metaphysics in  general.[12]  Although he argued that Leibniz's system was the best defense against Spinozism and skepticism, he also strongly suggested that it was by no means an adequate defense.  The only reason he defended Leibniz, he later confessed, is that the Berlin Academy was dominated by Leibnizians, who would never have awarded a prize critical of their  founder.[13]  His real convictions were that Spinoza's system is the epitome of abstract thinking, though it suffers from irresolvable problems that demonstrate the inadequacies of all  metaphysics.[14] 