Human brains are making the human world smarter and smarter, so that they (the brains) can be dumb in peace. Or rather, we are progressively altering our environment so that our brains, which are good at pattern-matching, at sensory recognition, and at the manipulation of objects in the world, can support intelligent choice and action by their participation in much larger networks. Human development is a process in which the brain becomes deeply tuned to the available environmental surround, be it pen, paper and sketchpad, or PC, Palm Pilot and designer software. As the century closes, and our typical, reliable environmental props and supports become ever more sophisticated and interlinked, so the mental machinery that makes us who we are is becoming ever more extended, interanimated and networked. In the near future, software agents whose profiles have evolved alongside those of a specific individual will count as part of the individual person. To say that I use those software agents will be strictly false. Instead, my brain and the various personalized manifestations of new technology will constitute integrated thinking things. I will no more be the user of these close-knit technologies than I am the user of the various sub- systems already existing within my biological brain. Instead, better to see both those sub-systems and these close-knit external technologies, as together constituting a spatially extended kind of user or person. The next step may be, as Rodney Brooks suggests, to put as much of that technology back inside the biological membrane as possible. This buys easier portability without changing the real state of affairs. We are already (mental) cyborgs.