recollections of words, accumulated in memory, are called up by the sound-impression and come to strengthen its effect. But if the conversation to which I listen is, for me, only a noise, we may suppose the sound increased as much as we like: the noise will be none the more intelligible for being louder. I grant that the memory of a word will be called up by the sound of that word: yet it is necessary, for this, that the sound of the word should have been heard by the ear. How can the sounds perceived speak to memory, how can they choose, in the storehouse of auditory images, those which should come to rejoin them, unless they have been already separated, distinguished,—in short, perceived,—as syllables and as words?
This difficulty does not appear to have been sufficiently noticed by the theorists of sensory aphasia. For in word deafness the patient finds himself, in regard to his own language, in the same position as we all are when we hear an unknown tongue. He has generally preserved intact his sense of hearing, but he has no understanding of the words spoken to him, and is frequently even unable to distinguish them. The explanation generally given of the disease is that the auditory recollection of words has been destroyed in the cortex, or that a lesion, sometimes transcortical, sometimes sub-cortical, hinders the auditive memory from evoking the idea, or the perception from uniting with the
