Such conflicts are built into the nature of the nervous system itself, for the early blinded adult who has spent a lifetime adapting and specializing his brain must now ask his brain to reverse all this. (Moreover, the brain of an adult no longer has the plasticity of a child’s brain—that is why learning new languages or new skills becomes more difficult with age. But in the case of a man previously blind, learning to see is not like learning another language; it is, as Diderot puts it, like learning language for the first time.)
