One very clear and complete case of the kind I have, however, encountered. This was a polyglot physician known as the author of several works, who for many years had lived among books and manuscripts. He has no trace of typographical vision, but all words “sound in his ear.” He can neither read nor compose without articulating; as the interest of his book or work grows upon him he speaks aloud—“He must hear himself.” In his dreams there are few or no visual images; he hears his voice and that of his interlocutors: “His dreams are auditory.” None of my words, even when semi-concrete, evoked visual images. In most cases the auditory type is not clear. For very general terms the heard word alone exists, but in proportion as the concrete is approached, the sound is accompanied by an image; thus returning upon our former type. It is worth while to note that the term _flatus vocis_ “_nomina_,” first employed in the Middle Ages and which has since become the formula of Nominalism, seems by its nature to indicate that it was originally invented by persons who belonged to the auditory type, and I may even hazard an hypothesis. The typographical visual type did not exist (printing not being invented); it is true that a substitute might have existed in the _graphic_ visual type (reading of manuscripts). But considering that in the Middle Ages instruction was essentially oral, that learning came rather through listening than by reading, that the oratorical jousts and arguments were daily and interminable, it is undeniable that the conditions for developing the auditory type were highly favorable here. I need hardly say that the three types described above are rarely met with in the pure and complete form. As a rule a mixed type prevails: a concrete image for certain words, and typographical vision, or auditory images, for others. To sum up: all cases seem to be capable of reduction to the following: (1) The word heard; beyond this, _nil_ (we shall subsequently have to examine this “nothing”); (2) typographical vision alone; (3) the same, accompanied by a concrete image; (4) the word heard, accompanied invariably by a concrete image. 4. Prior to the commencement of this inquiry I felt much hesitation on one point: should one in questioning use general _words_ or general _propositions_? I decided in favor of words because these are brief, simple, isolated, and undisguised, and have the advantage of being understood directly, while they in no way suggest to the subject what line he is to follow.