I. Natural Science and Its Boundaries

In the ordinary way we speak of five senses only, to which one or two inner senses are added by modern psychology. External science presents no complete system of the senses. I shall be speaking to you some time on this subject[^1] and will now say only that it is an illusion to believe that understanding of the sounds of speech is implicit in the sense of hearing, or in the organisation which is supposed by modern physiology to account for hearing. Just as we have a sense of hearing, we have a sense of speech— a sense for the sounds of speech. By this is meant the sense which enables us to understand what is perceived in the sounds of speech, just as the auditory sense enables us to perceive tones as such. And if some day we have a really comprehensive physiology, it will be known that this sense for the sounds of speech is entirely analogous to the other, that it can rightly be called a sense on its own. It extends over a larger area within the human organism than several of the other, more localised senses, but for all that it is a definitely circumscribed sense.