The arms are a partial snapshot of Mike's body, the material culture of his back-and-forth relationship with the shapes of his external world. That's why the term assistive technology is easy shorthand but ultimately both redundant and misleading—because assistance is universal whenever we talk about tools. The way the body and machine work together is much more aptly expressed by another name for prosthetics: adaptive technology. Tools don't run the show; they work together with bodies in a mutual exchange of adaptation.

A use-centered lens recasts the meaning of prosthetics when they land in our own lives, compelling us to think both about the material of the object and about the real wonder that's happening with all replacement parts: the wonder of human adaptation. What the gizmo does or doesn't do will always pale in comparison to the real miracle at hand—each body, endlessly plastic, responsive, operating with and through technologies of all kinds to get its tasks done in a resourceful mix of workarounds, glitch-ridden patchworks, quick fixes, and slow evolutions. A more meaningful perspective on tools takes into account not only technological effects or how many units are bought and sold but the whole context of use and adaptation: when and how people opt in or opt out, access to supplies for repair, local customs, and always—always—who has the power to decide.