How does Nicholson Baker use imagery in The Mezzanine: A Novel?

Imagery:

"They knew that the outer surface of truth is not smooth, welling and gathering from paragraph to shapely paragraph, but is encrusted with a rough protective bark of citations, quotation marks, italics and foreign languages, a whole variorum crust of "ibid.'s" and "compare's" and "see's" that are the shield for the pure flow of argument as it lives for a moment in one mind. They knew the anticipatory pleasure of sensing with peripheral vision ... Digression—a movement away from the gradus, or upward escalation, of the argument—is sometimes the only way to be thorough, and footnotes are the only form of graphic digression sanctioned by centuries of typesetters."