It is a persistent thought of Solomon Maimon, repeated several times by him in various connections, that while perception is a process occurring in time and subject to the mode of time, pure thought emerges instantly, at one stroke as it were, and is not a temporal process at all. In view of the prominence that Maimon gives to this distinction between perception and pure thought, two questions demanding elucidation necessarily arise. First, what is the source and origin of this idea? And second, what is the importance of this idea and its systematic place in Maimon's thinking as a whole? In answering these questions we may even gain clarification of Maimon's conception of a priori thought as distinct from sense perception.