Clinical Manual of Mental Diseases

just mentioned, and expressed in a less pretentious manner. It is certainly satisfactory, however, to note that Dr. Clark has considered the importance of a chapter on mental physiology, and that he has been at especial pains to elucidate the frequently obscure terms, illusion, hallucination, and delusion. It is not stated with sufficient clearness that an illusion depends upon the peculiar circumstances under which the object is presented, and not upon a faulty process of sense-perception. We do not like the term "insane illusion"; if an illusion cannot