Ludwig Wittgenstein
Since Wittgenstein thought that the Tractatus had solved all the problems of philosophy, he left philosophy and returned to Austria to train as a primary school teacher. Wittgenstein had unrealistic expectations of the rural children he taught, and had little patience with those children who had no gift for mathematics. But he had good results with children that were interested, especially boys. His severe disciplinary methods led to disagreement with some of his students' parents, and eventually he resigned his position and returned to Vienna, feeling that he had failed as a school teacher.