It is important to point out that Deleuze is a philosopher both expounding and commenting on Bergson's philosophy. In this book he attempts to connect together the important aspects of Bergson's work ranging from his very earliest treatise "Time and Free Will(TFW)", "Matter and Memory(MM)" to "Creative Evolution(CE)". These are the major texts but he also considers the others such as "Mind Energy", "The Creative Mind" and "The Two Sources of Morality and Religion". <br /> <br />The first of these introduces the concept of duration which is significantly different from the modern idea of time. It is Deleuze's task to join together Bergson's earliest idea of duration and to both see how this concept changes within each of the major texts as well as how it connects them. For example, the idea of duration firstly assumed a kind of psycholigical time or the time the human being actually experiences in his/her everyday life. This is duration in TFW. In MM, Bergson attempts to connect the mind and the body without necessarily letting go of these dualisms but by bypassing them. In CE, duration becomes something physical rather than purely subjective. Bergsonism attempts to connect these issues in a coherent framework linked to the idea of difference and virtuality. The concept of virtuality maintains its mystery throughout perhaps because the idea of wholeness only makes sense as long as it is never totally explicit. This comes out more clearly in Bortoft's "The Wholeness of Nature". <br /> <br />Deleuze's book succeeds in some ways but not in others, maybe this is the reason why he continues to elucidate his work in books such as "Difference and Repetition". Nonetheless a worthy read.