Martin Heidegger (1889-1976) is one of the most influential and controversial thinkers of the twentieth century. Born in 1889 to a Catholic family from Messkirch in Baden, Germany, Heidegger’s early life was marked by an intense interest in religion. From a young age he wanted to become a priest. This culminated in two years of theological study at Freiburg University, but Heidegger ultimately changed paths. In 1911 he began studying natural science and mathematics, which led to a doctorate in philosophy with a dissertation entitled The Doctrine of Judgment in Psychologism (1913). Heidegger’s goal was to be appointed as Freiburg’s professor in Catholic philosophy. His qualifying dissertation [Habilitationsschrift] on John Duns Scotus, a medieval philosopher and theologian, did not get him the post and so in 1915 Heidegger began his teaching career as a lecturer at Freiburg. It is at this time that Heidegger developed a personal relationship with Edmund Husserl, the founder of phenomenology. Heidegger’s work on Duns Scotus had been influenced by Husserl’s thought, but it was not until this time at Freiburg before and after World War I that Heidegger shifted his interests from Catholic philosophy to phenomenology.