Historically and intellectually there are complex connections between phenomenology and the later manifestations of existentialism. The phenomenology of Husserl was one of the major influences on Sartre, although Sartre came to reject some of Husserl's most distinctive doctrines. Some of the connecting and discussed doctrines are: that the defining feature of consciousness is intentionality so that every and only acts of consciousness are directed to a meant or intended object; the nature of the ego or I; the question of which is logically prior, essence or existence; and the possibility and adequacy of a disinterested or pure transcendental conceptualization of reality or being.

Husserl

Edmund Husserl (1859–1938) was born in Prossnitz, a village in Czechoslovakian Moravia, at that time part of the Austrian Empire. His early university studies at Leipzig and Berlin were in mathematics, and he received his PhD in mathematics in 1881. He also attended the philosophy lectures of Wilhelm Wundt at the University of Leipzig. Husserl decided to devote himself entirely to philosophy and he moved to Vienna, where he attended philosophy lectures by Franz Brentano (1838–1917), at which students were acquainted with the philosophy of David Hume and John Stuart Mill. Husserl taught at the universities of Halle and Göttingen, and from 1916 to 1929 at Freiburg, where he spent the rest of his life. Husserl was an important influence on Martin Heidegger (1889–1976), who became Rector of Freiburg University in 1933.