The book opens with a straightforward journey down physics ladder of scale. It moves outward from a countryside field to the cosmic web and the far edge of the observable universe. Then it turns inward, from the skin and cells of your hand to atoms, quarks, and finally to the scale at which current theory begins to lose coherence.
At every rung of the ladder, the same question returns, what is it made of? The answer changes with scale, and the change in language is part of the point.