WHEN I TALK about Gilles Deleuze's luminist philosophy, this luminism concerns two aspects of Deleuze's work. The first, conceptual aspect has to do with how Deleuze develops concepts from within registers of light, and with his use of both philosophical and scientific theories of light to position his philosophy within the overall philosophical field: his philosophy's conceptual light. The second aspect concerns the overall sentiment of Deleuzian philosophy. In this context, luminism stands for affirmation and for joy. For the warmth that, at all times and everywhere, suffuses Deleuze's thought. For a love of the world and of the living, and for a philosophy that aims, at all moments, to be adequate to the luminosity of that world: his philosophy's affective light. Although Deleuze's thought never shies away from coldness and cruelty, and although it knows pain, illness, suffering and death on a very intimate and personal level, it is never on the side of and it never celebrates negativity, or what Spinoza would consider to be bad encounters. It is a fundamentally positive thought. There is no dark romanticism in Deleuze's philosophy. No apocalypticism.

My intuition is that it is possible to develop a coherent image of Deleuze's philosophy from two of its conceptual leitmotifs: light and crystals. While each of these can function as an Ariadne's thread through Deleuze's work, if taken together, they can be more than that.