The three-volume "Philosophy of Symbolic Forms" is the outstanding work in which Cassirer completed the transformation of traditional transcendental philosophy into cultural philosophy. In place of purely rational cognition, which had always had primacy in the philosophy of the modern era, there is a plurality of symbolic forms, in each of which a specific spontaneity of the human spirit is manifested. In the third, concluding volume of the "Philosophy of Symbolic Forms" (1929) Cassirer expands the concept of cognition, which had determined the first phase of his thinking with the problem of cognition in the philosophy and science of modern times. While there the "exact" science was the center of interest, the Philosophy of Symbolic Forms progresses to an expansion of the concept of "theory" itself and assigns theoretical F.