This Book was written during a time when people like Paul Broca and Wernicke, were discovering that damage to specific areas of the brain could affect specific functions while keeping most every other function in tact. In fact, it sounds as though Jennings is describing Broca's, or Wernicke's aphasia, both of which, sort of fit Mr. Candy's behavior. If this is the case Candy's memory would be in tact, he would just be having trouble finding the words to express himself.