In our best estimation regarding the history of comics, the panel existed long before the page (and long before the written word, for that matter). Let’s imagine our ancestors huddled closely around a fire. They stare at a cave wall lit only by the warm, flickering light of the flames. To our right, we hear, “I’m hungry. Let’s hunt.” To our left, “Naw, hunt later. Let’s rest.” And then there’s us, in the center, speaking after a deep sigh, “I don’t know. I think I’m going to scrape this dirty stick on that wall and draw a story about my day.” The first cartoonists were not worried about the size or shape of the panel. Page layout, gutter spacing, and all the quirks of modern comics were far from their minds. It was not until much later that we started thinking of the panel as a box in which to put all our things. Before long, cartoonists were lining these boxes up to create classic comic strips, stacking them in tiers to make six- and nine-panel grids, and experimenting with complex visual architectures in order to bring intricate, nuanced fictions to life on the page. All these years later, though,...