Gilles Deleuze was a French philosopher who wrote on philosophy, literature, film and fine art. Deleuze's closest working relationship was with Felix Guattari (1930–1992), a French philosopher and psychotherapist, with whom he co-authored a number of important books. Something in the world forces us to think, and for Deleuze that something is the provocation arising from an encounter with difference. One can go into the thinking of Deleuze by looking at some of his most important concepts and the language he uses to talk about them – and as ever it is through getting a new language that we can also get a new way of thinking. Behind Deleuze's delight in the prospect of new thought, nomadic roaming through smooth space and the unpredictability of experimentation is a desire to contest and undermine power relations in modern societies.