“Life” was a major theme for Deleuze, so much so that he would say at one point: “Everything I’ve written is vitalistic, at least I hope it is” (N 143). But before we get out the pitchforks at this uttering of a forbidden word, we should remember Deleuze’s love of provocation, and read the beginning of the passage to see his idiosyncratic notion of vitalism: “There’s a profound link between signs, life, and vitalism: the power of nonorganic life that can be found in a line that’s drawn, a line of writing, a line of music. It’s organisms that die, not life. Any work of art points a way through for life, finds a way through the cracks” (N 143).

In this chapter we will skirt the relation of life and art, however, and instead focus upon Deleuze’s writings that are aimed at life as it is understood in the biological register. We’ll begin with a guide to some key biophilosophical investigations in Deleuze’s single-authored masterpiece, Difference and Repetition: chapter 2 on organic syntheses and organic time, and chapter 5 on embryogenesis. Then, in the second part of the chapter, we will consider several biophilosophical themes in Deleuze and Guattari’s Anti-Oedipus and A Thousand Plateaus, addressing “vitalism,” “life,” “nature,” “content and expression,” “evolution and involution,” “milieus, codes, territories,” “non-organic life,” “body without organs,” and “organism.”