Other sixteenth-century writers shared Montaigne’s fascination with the unstable. What was unusual in him was his instinct that the observer is as unreliable as the observed. The two kinds of movement interact like variables in a complex mathematical equation, with the result that one can find no secure point from which to measure anything. To try to understand the world is like grasping a cloud of gas, or a liquid, using hands that are themselves made of gas or water, so that they dissolve as you close them.

