I trust to be excused if in these days of pathological and anatomical research, I ask you to examine with me to-night a group of symptoms. I need hardly say that the study of symptoms must ever be of importance in the treatment of disease, and especially of that disease with which we are all concerned, and although to the general medical public the subject of hallucinations of hearing may have no special interest, yet the members of this association know that they characterize a very peculiar and well-defined class of patients, and that, common as they are, their nature and pathology are uncertain and mysterious. I have, therefore, chosen them, as the subject of a paper, chiefly for the purpose of promoting discussion concerning them, and eliciting the opinions of those here present.