Every nameable thing, act, or relation has numerous properties, qualities, or aspects. In our minds the properties of each thing, together with its name, form an associated group. If different parts of the brain are severally concerned with the several properties, and a farther part with the hearing, and still another with the uttering, of the name, there must inevitably be brought about (through the law of association which we shall later study) such a dynamic connection amongst all these brain-parts that the activity of any one of them will be likely to awaken the activity of all the rest. When we are talking as we think, the _ultimate_ process is that of utterance. If the brain-part for _that_ be injured, speech is impossible or disorderly, even though all the other brain-parts be intact: and this is just the condition of things which, on page 37, we found to be brought about by limited lesion of the left inferior frontal convolution. But back of that last act various orders of succession are possible in the associations of a talking man's ideas. The more usual order seems to be from the tactile, visual, or other properties of the things thought-about to the sound of their names, and then to the latter's utterance. But if in a certain individual the thought of the _look_ of an object or of the _look_ of its printed name be the process which habitually precedes articulation, then the loss of the _hearing_ centre will _pro tanto_ not affect that individual's speech. He will be mentally deaf, i.e. his _understanding_ of speech will suffer, but he will not be aphasic. In this way it is possible to explain the seven cases of _pure_ word-deafness which figure in Dr. Starr's table. If this order of association be ingrained and habitual in that individual, injury to his _visual_ centres will make him not only word-blind, but aphasic as well. His speech will become confused in consequence of an occipital lesion. Naunyn, consequently, plotting out on a diagram of the hemisphere the 71 irreproachably reported cases of aphasia which he was able to collect, finds that the lesions concentrate themselves in three places: first, on Broca's centre; second, on Wernicke's; third, on the supra-marginal and angular gyri under which those fibres pass which connect the visual centres with the rest of the brain[40] (see Fig. 17). With this result Dr. Starr's analysis of purely sensory cases agrees. [Illustration: FIG. 17.]