Another quote I enjoy:

The specificity is the same at one level: the affordance of the logic of time governs writing, and the affordance of the logic of space governs the image. Within that, there is the possibility of generic variation. And the generic variation of the ensembles, in each case, produce an overall difference of a significant kind (115).

and

In that new communicational world there are now choices about how what is to be represented should be represented: in what mode, in what genre, in what ensembles of modes and genres and on what occasions. These were not decisions open to students ... some twenty years ago (117).

Perhaps part of the task writing teachers should be doing is helping students learn how to choose in this multimodal culture. Hmmm.