Gilles Deleuze, answered from the texts and cited to the page.
The question invites a kind of spiral — the book's subject and its method are the same thing, which is perhaps the first thing to say. The deepest claim is that difference has always been subordinated to identity and resemblance in the philosophical tradition. Plato is the decisive moment: the Platonic system is erected on the distinction between the original and the image, the model and the copy, and within this framework difference can only appear in third place, as the comparative play between two similitudes.1
But the more important Platonic distinction — the one that actually does the philosophical work — is not between model and copy at all. It is between two kinds of images: the icon (the copy that resembles the Idea from within, that earns its place through internal similitude) and the simulacrum (the false pretender, the phantasm, whose semblance is purely external).2
Platonism is erected on the wish to hunt down the simulacrum, to send it back to the bottomless ocean along with the Sophist who embodies it. What I argue is that the overturning of Platonism means affirming the simulacrum on its own terms — not reversing the hierarchy of copy over original, but showing that the simulacrum has its own being, constituted by internal difference rather than by resemblance to any transcendent model.
Repetition enters here because the eternal return is not the return of the Same. It is the same of the different, the one of the multiple — a formula that sounds paradoxical only so long as identity is taken as primary.3 What returns are not identities prolonged through time but pre-individual singularities, and for that return to be grasped as repetition at all, the dissolution of all prior identities is presupposed.4
There is no first time standing outside repetition that repetition merely copies; origins are assigned only in a world that has already been precipitated into universal ungrounding.5 The book then has to account for what goes wrong — why we keep mistaking repetition for the return of the same, why difference keeps collapsing back into negation.
The answer is that negation is a shadow, an illusion produced when problems are translated into hypotheses. There is a non-being in the book — the (non)-being of the problematic, written as 0/0 — but it is not the being of the negative.6 Problems are not contradictions; they are structures of differential singularities, and when they get rendered as propositions flanked by their double negatives (whether it is fine, whether it is not fine), the real structure of the problem is betrayed by its shadow.7
At the level of repetition itself, the book distinguishes types rather than instances. The frontier is not between a first time and its repetitions but between modes of repetition — between the repetition of the Before (one repeats because one does not know, does not remember, is not yet capable) and the repetition of the During (one becomes equal to the image of the action, the ego projects itself into an ideal).8
Christian repetition against atheist repetition, Kierkegaard against Nietzsche: the difference is not numerical but fundamental, a difference in kind between repetitions that operate once and for all and repetitions that operate for all times.9 It is when repetition bears upon repetitions — when it assembles them and introduces difference between them — that it acquires its power of selection.10
The book is, in short, an attempt to think difference in itself and repetition for itself, without subordinating either to identity, resemblance, opposition, or analogy. Those four categories — the four shackles of representation — are what the book works against. What it works toward is harder to name in a sentence, which is perhaps as it should be: a transcendental empiricism in which Ideas are immanent differential structures, multiplicities of singularities, problems that are never exhausted by their solutions.
difference comes only in third place, behind identity and resemblance, and can be understood only in terms of these prior notions. Difference is understood only in terms of the comparative play of two similitudes: the exemplary similitude of an identical original and the imitative similitude of a more or less accurate copy.Difference and Repetition, p. 161
the true Platonic distinction lies elsewhere: it is of another nature, not between the original and the image but between two kinds of images [idoles], of which copies [icônes] are only the first kind, the other being simulacra [phantasmes].Difference and Repetition, p. 161
The eternal return is the same of the different, the one of the multiple, the resemblant of the dissimilar.Difference and Repetition, p. 161
the reprise of pre-individual singularities which, in order that it can be grasped as repetition, presupposes the dissolution of all prior identities.Difference and Repetition, pp. 264–265
origins are assigned only in a world which challenges the original as much as the copy, and an origin assigns a ground only in a world already precipitated into universal ungrounding.Difference and Repetition, pp. 264–265
There is a non-being, yet there is neither negative nor negation. There is a non-being which is by no means the being of the negative, but rather the being of the problematic. The symbol for this (non)-being or?-being is 0/0.Difference and Repetition, pp. 264–265
The negative is an illusion because the form of negation appears with propositions which express the problem on which they depend only by distorting it and obscuring its real structure.Difference and Repetition, pp. 264–265
The repetition of the Before is defined by default or in a negative manner: one repeats because one does not know, because one does not remember, etc... The repetition of the During is defined by a becoming-similar or a becoming-equal: one becomes capable of performing the action, one becomes equal to the image of the action.Difference and Repetition, pp. 384–385
Christian repetition is opposed to atheist repetition, and Kierkegaardian to Nietzschean, for in the case of Kierkegaard it is repetition itself which takes place once and for all, whereas according to Nietzsche it operates for all times. Nor is this simply a numerical difference; it is, rather, a fundamental difference between these two kinds of repetition.Difference and Repetition, pp. 384–385
once repetition bears upon repetitions, once it assembles them all and introduces difference between them, it thereby acquires a formidable power of selection.Difference and Repetition, pp. 384–385