If, then, an odour can induce such emotional changes without attracting attention to itself, the suggestion is not, after all, so very far-fetched that an emanation proceeding from the worshippers at the moment of the elevation of the Host in a Roman Catholic church may be transmitted to the bystanders through the olfactory door to induce in them an emotion similar to that felt by the initiated. It may be objected that Goethe’s experience and that of my friend are not alike, since Goethe plainly, though tardily, became aware of a real odour. It must be remembered, however, that Goethe was a scientist and naturally gifted, besides, with an unusual power of introspective analysis. He found the cause of his disturbance because he sought for it. Moreover, we learn from Havelock Ellis that during religious excitement a real (and pleasant) odour is sometimes perceptible in the atmosphere around the faithful. May it not also be the same kind of influence, transmitted in the same way, that dominates the mind, in company with impressions received by sight and hearing, when we are in the vicinity of other people? Our study of smells has brought us, to be sure, into a strange region of psychology, for it is possible that we have here one explanation of the mysteries of crowd-psychology, of those unreasonable waves of passion that sometimes sweep through masses of people and lead to all manner of strange happenings, like crusades and holy wars; _autos-da-fé_; witch-burnings; lynch-murders; State-prohibition; spiritualistic manifestations; and other miracles. (The somewhat uncanny “sense” we have when some one else is present in what we suppose to be an empty room may be olfactory in origin, but it has generally seemed to me that it is due rather to an alteration in the echo of the room, a change in its normal sound-picture. If the room is a strange one to us, I do not think we so readily become suspicious of the presence of an unseen and unexpected visitor.) CHAPTER VIII THEORIES OF OLFACTION (_The Pièce de Résistance_) The anatomical structure of the olfactory end-organ in the nose is, as we saw in Chapter II., simple. Contrast it with the eye. Here we have what is obviously an optical instrument, with lens, iris diaphragm, dark walls, and sensitive plate complete—a photographic camera, in a word. Contrast it also with the ear, which is an acoustic apparatus reminding us in its detail of a recording gramophone leading to a closed box in which are what look like a series of resonators, like the wires of a piano. In the antechamber of each of those organs the physical vibrations to which they respond undergo considerable modification before they reach the sensory cells.