Born to Jewish parents in what is now the Czech Republic, Edmund Husserl began as a mathematician, studying with Karl Theodor Weierstrass and receiving a doctorate in 1881. He went on to study philosophy and psychology with Franz Brentano and taught at Halle (1887--1901), Gottingen (1901--16), and Freiburg (1916--29). Because of his Jewish background, he was subject to persecution by the Nazis, and after his death his unpublished manuscripts had to be smuggled to Louvain, Belgium, to prevent their being destroyed. Husserl is the founder of the philosophical school known as phenomenology. The history of Husserl's philosophical development is that of an endless philosophical search for a foundational method that could serve as a rational ground for all the sciences. His first major book, Philosophy of Arithmetic (1891), was criticized by Gottlob Frege for its psychologism, which changed the whole direction of Husserl's thinking. The culmination of his next period was the Logical Investigations (1901). His views took an idealistic turn in the Ideas Toward a Pure Phenomenology (1911). Husserl wrote little from then until the late 1920s, when he developed his idealism in a new direction in Formal and Transcendental Logic (1929) and Cartesian Meditations (1932). His thought took yet another turn in his late lectures published as Crisis of the European Sciences (1936), which emphasize the knowing I's rootedness in "life world." Husserl's influence in the twentieth century has been great, not only through his own writings, but also through his many distinguished students, who included Martin Heidegger, Maurice Merleau-Ponty, Jean-Paul Sartre, Eugen Fink, Emmanuel Levinas, and Roman Ingarden.