The simplest brain-machine interface, or at least the one we can use the most readily, is the human hand. We’ve structured pretty much the entirely of computing around the input it’s possible to produce with our hands, and now to a lesser extent with our voices. But hands and voices are limited. Words, whether spoken or typed, are just representations of our real intentions, and the practice of a moving the image of a mouse-pointer within a simulated physical space creates even more abstraction between user and program. Translating our thoughts to computer-style commands, and then physically inputting them, is a slow process that takes time and attention away from the task at hand.