Anyone who wonders about the right way to read Deleuze, about whether we should search for system and clarity in his works, should investigate the relation between his seminars and his written works.
Unfortunately we do not have transcriptions for most of his seminars of the 70s, save for a few exceptions. Basically we are limited to the last eight years of his teaching. This is a limited sample, but it is enough to get an idea of Deleuze’s conceptual style.
I was lucky enough to attend Deleuze’s seminars from 1980 to 1986, centered on minority struggle and war machines (treated in A THOUSAND PLATEAUS), cinema, and Foucault. I found the lectures clear, in that each subject was well-explained and that Deleuze replied patiently and pedagogically to most questions, and also obscure, in that the place of each concept or series of concepts in the overall system was not always evident.
The seminars had the temporality of a voyage of discovery. I remember Deleuze keeping a certain suspense. For example in the cinema classes, during the long discussion of the movement image referring tantalisingly to the possibility of a ifferent sort of image. Or in some of the Foucault seminars, ending the class by asking is this all there is, or is there something more?, before going on the next week to discuss how a new phase in the work and a new level of explanation was motivated by what went before.
The seminars gave you the experience of constantly discovering new ground, but with no overall map. So despite attending them assiduously I was also eager for the books to come out so I could gain even more clarity from the systematic overview they provided. The books are more difficult in the details, being conceptually dense and linguistically highly compressed, but more perspicuous in the framework provided.
My conclusion is the rather banal one that in Deleuze’s opus there is a trade-off between the (pedagogical) phenomenological clarity of the seminars and the systematic clarity of the books. This is a typological division, and one should not overemphasise the sites of its instantiations. It is easy to see the same sort of differences inside a single book, and the variable alternation between phenomenological and systematic exposition imparts its particular conceptual rhythm to each of Deleuze’s books.