Two of the most influential philosophies of modern times seem to stand in radical opposition to each other: Spinoza and Hegel, philosophically speaking either the infinite, unchanging substance or the infinite, productive negation of the negation. What happens when Hegel meets Spinoza? Hegel stated that one is either a Spinozist or not a philosopher at all. Spinozists like Althusser or Deleuze argued that Hegel introduced a thinking of identity through the back door. This book attempts to give voice to both sides and to view each side from the critical perspective of the other.