“sit as little as possible; do not believe any idea that was not born in the open air and of free movement.”

We can clarify and codify the body’s messages by keeping an “interoceptive journal”—a

Elements of the world outside may effectively act as mental “extensions,” allowing us to think in ways our brains could not manage on their own.

These two metaphors—brain as computer and brain as muscle—share some key assumptions. To wit: the mind is a discrete thing that is sealed in the skull; this discrete thing determines how well people are able to think; this thing has stable properties that can easily be measured, compared, and ranked.

thing: thought happens not only inside the skull but out in the world, too; it’s an act of continuous assembly and reassembly that draws on resources external to the brain. For another: the kinds of materials available to “think with” affect the nature and quality of the thought that can be produced. And last: the capacity to think well—that is, to

forms of social interaction that allow other people’s cognition to augment our own; they also supply guidance on how to offload, externalize, and dynamically interact with our thoughts—a much more effective approach than doing it all “in our heads.”

world is full of far more information than our conscious minds can process.

“people with greater sensitivity to interoceptive signals.”

The literature on the extended mind suggests a different view: experts are those who have learned how best to marshal and apply extra-neural resources to the task before them. This