Lawvere has many times stressed the need to find a correct "definition" of large topoi (or topoi of spaces). It is classical the distinction between topoi of spaces (large) versus space (or spatial) topoi (small) as for example the large Zariski topos versus the small Zariski topos (or the same for the etal topology, although in this second case neither is spatial in the strict technical sense) I just bring this classical examples for consideration in this thread e.d. [For admin and other information see: http://www.mta.ca/~cat-dist/ ]