One could say that every philosopher has two philosophies: his [sic] own and that of Spinoza. 
Spinozism or no philosophy at all. 
I. “We have not yet begun to understand Spinoza,” Gilles Deleuze once claimed, “and I myself no more than others,”  noting elsewhere that “the greatest philosophers are hardly more than apostles who distance themselves from or draw near to this mystery.” 
Here one question eclipses all others, or serves to focus them: What would it be to have an adequate idea of Spinoza?
II. Philosophy is the very vertigo of immanence. That formula complements one of Deleuze’s: “Immanence is the very vertigo of philosophy.”  Immanence is not philosophy, nor philosophy immanence. But there is in the passage from one to the other a modification of sense that is not without significance. It is perhaps for that reason that the two formulas are best read together. At the point of vertigo.
But why vertigo? What about philosophy, much less immanence, may be said to be vertiginous? Daniel Heller-Roazen has isolated the two components all enigmas share: “opacity and the hidden principle of their interpretation. That summary may appear willfully paradoxical,” Heller-Roazen comments, “yet enigmas verify its truth”: Were an enigma “immediately intelligible, it would be none at all,” yet were an enigma “solely solvable by means of knowledge extrinsic to its construction, it, too, could hardly be called an ‘enigma.’” 
Immanence is the very vertigo of philosophy because immanence is the very paradigm of the enigma.
Deleuze’s formula is found in a work Deleuze titled Spinoza and the Problem of Expression. “By taking the ‘problem of expression’ as his central concern, Deleuze announces the ingenuity of his approach. Nowhere in the myriad definitions that the Ethics comprises is ‘expression’ defined. Yet the verb form of the concept appears on the very first page in the definition of ‘God’: ‘By God I mean an absolutely infinite being; that is, a substance consisting of infinite attributes, each of which expresses eternal and infinite essence.’” 
More remarkable yet, “as soon as it is introduced into Deleuze’s argument, the concept ‘expression’” is
immediately bifurcated into two senses. The virtue of this concept for Deleuze is that it provides a single name for two heterogeneous processes, explication and implication. Deleuze argues that in Spinozism the modes, as affections of substance, effectively explicate substance. But it is equally true that each modal modification implicates substance in turn. The usual connotations of these two words are fully in force in Deleuze’s reading; substance is effectively elaborated through, that is, explicated by, the modes. But the modes implicate substance, in that they impinge on its putative autonomy, never leaving it unchanged. […] Deleuze’s point is that in Spinoza substance is in an incessant state of unfolding (explication) via the modes, and folding back in on itself (implication) as a result of these modal affections. 
To explicate is to implicate, for every implication follows from an explication, and every explication turns on how what it explicates is implicated in it.
Philosophy stands to immanence as explication stands to implication.
Philosophy: the vertigo of immanence in its expression.
III. “Philosophy is something that moves, that passes, and that takes place,” Pierre Macherey has written, “in a place where the connection between thoughts gestates, which, in the works themselves, escapes the specific historical conditions of their authors’ undertakings, and the understanding of this process diminishes the interest we might extend to their systematic intentions, because this process grasps them dynamically in the anonymous movement of a sort of collective project.”
“Spinoza” is the name given that anonymity by those who undergo its movement sub specie aeternitatis.
1. Henri Bergson, quoted in Michael Hardt, Gilles Deleuze: An Apprenticeship in Philosophy (Minneapolis: University of Minnesota Press, 1993), 130n3.
2. G.W.F. Hegel, quoted in Pierre Macherey, “Hegel Reads Spinoza,” Environment and Planning D: Society and Space 29 (2011), 223 [223-236].
3. Gilles Deleuze and Claire Parnet, Dialogues II, trans. Hugh Tomlinson and Barbara Habberjam (New York: Continuum, 2006), 12.
4. Gilles Deleuze and Felix Guattari, What is Philosophy?, trans. Hugh Tomlinson and Graham Burchell (New York: Columbia University Press, 1994), 60.
5. Gilles Deleuze, Expressionism in Philosophy: Spinoza, trans. Martin Joughin (New York: Zone Books, 1992), 180.
6. Daniel Heller-Roazen, Dark Tongues: The Art of Rogues and Riddlers (New York: Zone Books, 2013), 77.
7. Knox Peden, Spinoza Contra Phenomenology: French Rationalism from Cavaillès to Deleuze (Stanford: Stanford University Press, 2014), 210. Emphasis Peden’s.
8. Peden, Spinoza Contra Phenomenology, 211. Emphasis author’s.
9. Pierre Macherey, Hegel or Spinoza, trans. Susan M. Ruddick (Minneapolis: University of Minnesota Press, 2011), 3-4.