Regularities are not permanent markers of the world; often they are a ledge to rest before climbing onwards. To take the most obvious example, walking is nothing other than controlled falling. Each time you lift one foot, you are falling forward except that you land the other foot before you keel over. Balancing on one foot is an example of a metastable state, i.e., a state that is locally stable, but that will descend into a lower energy state if perturbed slightly. At each stage, an organism needs to point out the next metastable state before pushing toward it. The continuous dance of pointing and pushing defines dynamic regularities.

It takes a lot of effort to keep a metastable state in a position of dynamic equilibrium. Think of balancing a cricket stump or a badminton racquet on one finger: you have to keep moving your finger to make sure that the stump doesn’t fall down. Each metastable state defines a dynamic regularity; there is nothing permanent in the world that is available to “pick up,” so to speak, but at any given moment, there is a next step to be taken. While metastability is obviously true of walking, it is less obviously true of seeing and thinking as well. When you see an object, say, the famous Mona Lisa, your visual system picks up a temporary metastable regularity, which is a visual snapshot of the famous painting.

However, you might want to know more; perhaps her smile is so mysterious that you want a closer look.

That movement toward the painting destroys the earlier metastable percept and introduces a new one. The smile remains mysterious though; the old lady never reveals all her secrets,