Gilles Deleuze, answered from the texts and cited to the page.
Being is said in a single, univocal sense of all that is — where what differs is only the modal difference of beings. The univocity thesis is articulated through the Duns Scotus / Spinoza / Nietzsche lineage. The plane of immanence is the absolute horizon of philosophical thought; transcendence (Plato's Idea, Christian God, Kant's noumenal subject, Hegel's Absolute Spirit) is what philosophy must always be working against.12
Plato's "poisoned gift" was to introduce transcendence into the field of immanence; modern philosophy continues to suffer from this. Each great philosopher constructs a plane of immanence — Spinoza's substance, Bergson's duration, Nietzsche's will to power — and the construction is the philosophical work, not the discovery of a pre-given ground.
It is Anaximander who distinguishes between the two sides most rigorously by combining the movement of qualities with the power of an absolute horizon, the Apeiron or the Boundless, but always on the saIlle plane. Philosophers carry out a vast diversion of wisdom; they place it at the service of pure immanence. They replace genealogy with a geology.What Is Philosophy, pp. 44–45
In this modern moment we are no longer satisfied with thinking immanence as immanent to a transcendent; we want to think transcendence within the immanent, and it is from immanence that a breach is expected. Thus, in Jaspers, the plane of immanence is given the most profound determination as "Encompassing" [Eng/obant], but this encompassing is no more than a reservoir for eruptions of transcendence.What Is Philosophy, pp. 47–48
Held throughout the authorship, articulated most systematically in Difference and Repetition and the Spinoza books. The late essay "Immanence: A Life" (1995) is its purest statement: an "absolute immediate consciousness" that is the transcendental field stripped of subject and object. The geology-of-morals plateau in A Thousand Plateaus extends the immanence thesis into social-political registers; What Is Philosophy? gives the meta-philosophical articulation.