Immanuel Kant, the propounder of the critical philosophy, was born at Königsberg in East Prussia; he was the son of a saddler and, according to his own account, the grandson of an emigrant from Scotland. He was educated at the local high school, the Collegium Fridericianum, and then at the University of Königsberg, where he had the good fortune to encounter a first-class teacher in the philosopher Martin Knutzen. After leaving the university, about 1746, Kant was employed for a few years as a tutor in a number of families in different parts of East Prussia. He kept up his studies during this period and in 1755 was able to take his master's degree at Königsberg and to begin teaching in the university as a Privatdozent. He taught a wide variety of subjects, including physics, mathematics, and physical geography as well as philosophy...