 To see how Ideas are transcendental and immanent, we have to appreciate that an Idea is a concrete universal. In an early article on Bergson (“The Conception of Difference in Bergson” [1956]), Deleuze gave a particularly helpful example of this notion. In La Pensée et le Mouvant, Bergson had shown that there are two ways of determining what the spectrum of “colors” have in common. (1) You can extract from particular colors an abstract and general idea of color (“by removing from the red that which makes it red, from the blue what makes it blue, from the green what makes it green”). Or, (2) you can make all these colors “pass through a convergent lens, bringing them to a single point,” in which case a “pure white light” is obtained that “makes the differences between the shades stand out.” The former case defines a single generic “concept” with a plurality of objects; the relation between concept and object is one of subsumption; and the state of difference remains exterior to the thing. The second case, on the contrary, defines a differential Idea in the Deleuzean sense: the different colors are no longer objects under a concept, but constitute an order of mixture in coexistence and succession within the Idea; the relation between the Idea and a given color is not one of subsumption, but one of actualization and differenciation; and the state of difference between the concept and the object is internalized in the Idea itself, so that the concept itself has become the object. White light is still a universal, but it is a concrete universal, and not a genus or generality.