There is a design (or set of designs) on the right page. Then on the left foldout page, the design is broken down into a number of elements. You can't see it very well in this picture but they've broken this design into "painted sticks, stones and ropes typography," "diptych, triptych, etc," and "burning holes." Each of these elements is broken out and examples of that same element are given in the corresponding row. I'm amazed at how many of the elements show up in other designs and there are some interesting/weird ones: numbers becoming letters; chain link fence; potato type; lots of things piled up neatly; are these my hands?; and many more.
The idea is to explore the influences and inspirations for modern design. It's a brilliant concept and is nicely executed, using the metaphor of how we study anatomy. The introduction has a brief description of the history we've been studying so far. It drew my attention because it's kind of interactive which I've always been drawn to. I could spend hours looking through it. Can't wait for a snowy weekend!