Some brain damage produces fluent speech that makes no sense

In 1874, Carl Wernicke found that damage to one spot in the left temporal lobe leaves speech fluent and grammatically smooth but empty of real meaning — the mirror image of Broca's aphasia, where speech is halting but meaningful. This split showed language isn't run by a single brain region: production and comprehension live in separate areas. It became founding evidence for localizing language in the brain.

— Carl Wernicke, Der aphasische Symptomencomplex — 1874 monograph; see also Wernicke's area