My thesis in this text is that A. Ernst Cassirer outlines a philosophical theory that proves equally sensitive to historical change and to the consistency of conceptual thinking. B. Cassirer relies on the differential logic of an internally ruptured, and yet undivided “basis phenomenon.” Especially his reading of Goethe has led to the concept of the basis phenomenon existing in a differential symbolic mode. Cassirer's delineation of Goethe's conceptual trivium of Urphänomene — “experience,” “deed,” and “life” — underscores the conceptual rupture in the construction of any basis phenomenon. Furthermore, I argue that C. the Philosophy of Symbolic Forms, takes up Goethe's notion of basis phenomena and eventually turns it into a modern, pluralistic theorem about the interrelation of science and culture. Cassirer reaches this aim by (1) focusing on the question of philosophical inquiry as a basis phenomenon in the sense of a basic philosophical activity. I also argue that (2) Cassirer's view retains an essentially ambiguous character, as opposed to a fundamentalist notion of basis phenomena. It is important to see that (3) this ambiguity also informs Cassirer's notion of culture (the plurality of symbolic forms), as well as his delienation of the relation between culture and science.