Deleuze came from a long line of Continental philosophers concerned with various means of destabilizing essentialism (Spinoza, Nietzsche). At the same time each one felt there was something else to put in its place. For Deleuze it was the One-all which can be thought of as the totality of everything. This totality extends to the end of our physical universe and its conditions of possibility. Such a basic premise seems to harken to Plato and his theory of the realm of ideas and the difference between the intelligible and the sensible. Rightly so, as Deleuze feels he is overturning Platonism. In doing this he seeks to privilege the physical corporeal world by destabilizing the 'idea' of ideals. We get from Plato the impression that these ideals have some sort of stable ontological status (they're real, and they don't change). Furthermore, when they come down to physical reality they are never instantiated quite right. Deleuze saw this as a weak formulation of the real world of the virtual (his realm of ideas). For him any actualization (real physical observable world stuff) is a nexus of virtualities which are necessarily interacting imperfectly. This imperfection implies problems or areas in which the next actualization can let another virtuality intersect the previous virtualities.
On a moral/political level, Deleuze takes this idea (and a host of others) as a means of allowing him to reject Fascism in its macro (Nazi-esque) and micro (internalized capitalist) forms. He believed that we should cherish and accept the instability of the physical world and flow through the actualizations of virtuality instead of seeking to limit them. To limit and regulate them is to limit and regulate life and process.
Deleuze committed suicide by jumping from a window in 1995
In collaboration with Felix Guattari:
On Gilles Deleuze: