Deleuze and Parnet explain part of the meaning of assemblage (agencement) (1):
What is an assemblage? It is a multiplicity which is made up of many heterogeneous terms and which establishes liaisons, relations between them, across ages, sexes and reigns -- different natures. This, the assemblage's only unity is that of a co-functioning: it is a symbiosis, a 'sympathy'. It is never filiations which are important, but alliances, alloys; these are not successions, lines of descent, but contagions, epidemics, the wind. (Dialogues II, 69)
This passage from Deleuze and Parnet highlights the core idea of an assemblage bringing together heterogeneous pieces into a new whole. It also signals the important distinction for Deleuze between interiority and exteriority. DeLanda explicates this distinction as indicating the nature of the relations among the elements. "Interior" relations among things are essential, logical, or semantic; whereas exterior relations are contingent and non-essential. Identifying a pair as husband and wife is to identify an interior relation; identifying a pair as a female architect and a male night club bouncer is an exterior relation. This is what Deleuze and Parnet refer to when they refer to alliances, alloys, contagions, epidemics: conjunctions of otherwise independent things or processes.
