Brains interfaced to machines, where thought is used to control and manipulate these machines. This is the vision examined in this chapter. First-generation brain-machine interfaces have already been developed, and technological developments must surely lead to increased capabilities in this field. The most obvious applications for these technologies are those that will assist disabled people. The technology can help restore mobility and communication capabilities, thus helping disabled people to increase their independence and facilitate their participation in society. But how should this technology be employed: just to manipulate the world or also to leverage self-knowledge? And what will the technology mean for the rest of the population? These are some of the questions that are addressed in this chapter.