"juxtaposed pictorial and other images in deliberated sequence, intended to convey information and/or to produce an aesthetic response in the viewer." (Understanding Comics: The Invisible Art Page 9)After arriving at this definition (a discussion that takes a few pages and is extremely interesting), McCloud mentions a term that comics pioneer Will Eisner utilized in Comics and Sequential Art to describe comics, sequential art. Nonetheless, what’s important here is sequence. Comics are not simply the combination of words and pictures. On the contrary, comics don't require words at all. What they do require is sequence. In fact, comics are all about sequence and the magic that happens between the panels, something McCloud calls closure. With a sequence of images, a reader is required to perform some cognitive processing (closure) to build a narrative from the disparate parts (panels). Reading comics isn't like watching a movie which is simply experiential processing. To quote the very articulate and prolific Warren Ellis, comics happen "behind the senses" and require engagement by the reader. Something else important here that I haven't seen discussed is context. Each panel lends context to the other panels which helps the reader build the narrative. If closure is the act of creating the narrative, then this inter-contextuality serves as the building block that enables it.
I guess what brought this up is recent discussion on one of the Grand Comics Database (http://comics.org/) mailing lists about single panel cartoons. My contention is that single panel cartoons aren't really comics since there's no sequence. Sure, they contain both words and pictures, but there's no closure or inter-contextuality. It's simply a small piece of art, no more comics than if someone placed a word balloon on the Mona Lisa.
This is, of course, all fodder for my dissertation and future issues of Diary of Night, both of which I am still working on.
Enough rambling for now.