When you are dependent on recipes, you are a factory worker on the assembly line; when you possess ratios and basic technique, you own the company.
With ratios (1:2:3 makes a basic cookie dough using 1 part sugar, 2 fat, 3 flour), you need only remember the proportion of ingredients, and from there you can improvise. You're freed from books, recipe cards, or print-outs.
Or, as Ruhlman says about the 5:3 bread dough ratio (flour-to-water), "With this bread dough ratio, you don’t have a single recipe, you have a thousand. Ratios are the launching point for infinite variations."
Ruhlman's wife, Donna Turner Ruhlman, shot the photos, and word is that she is working on a poster that illustrates the baking and pastry ratios—where proportion is especially important.