A collection of essays and lectures concerning the nature of intuition, explaining how intuition can be used as a philosophical method. Intuition is described as a method of ‘thinking in duration’ which reflects the continuous flow of reality. Bergson distinguishes between intuitive and conceptual thinking, explaining how intuition and intellect may be combined to produce a dynamic knowledge of reality. Bergson distinguishes between two forms of time: pure time and mathematical time. Pure time is real duration. Mathematical time is measurable duration. Real time is continuous and indivisible. Mathematical time is divisible into units or intervals which do not reflect the flow of real time. According to Bergson, real time cannot be analyzed mathematically. To measure time is to try to create a break or disruption in time. In order to try to understand the flow of time, the intellect forms concepts of time as consisting of defined moments or intervals. But to try to intellectualize the experience of duration is to falsify it. Real duration can only be experienced by intuition. In the intellectual representation of time, a succession of distinct states or events is presented as a spatialized form of time. Time is conceptualized as an ordered arrangement of defined events, rather than as an endless flow of experience in an indivisible continuity. The intellect analyzes time as having measurable duration, but the flow of real time can only be known by intuition.