The novel, he says, is the culmination of an obscure apprenticeship to the signs the world emits. Right from the start, Deleuze insists that the novel is not about memory, as is commonly assumed, but signs. The laying bare of signs, through character and plot, is, of course, a traditional skill of writing a novel. However, it is Proust's feat to reveal the process by which these signs work and how we might discern the truth of our lives from them. However, to the degree that we achieve art, the relation of sign and meaning becomes closer.
Art is the splendid final unity of an immaterial sign and a spiritual meaning.
You can tell from this passage that Deleuze is not making concessions to the inattentive. Not even Alain du Botton. What Deleuze does make plain, however, is that the search for truth depends on more than intellect alone. The mistake of philosophy is to presuppose within us a benevolence of thought, a natural love of truth. Thus philosophy arrives at only abstract truths that compromise no one and do not disturb.