The Modern Art of Taming Wild Horses/Chapter 8
SUGGESTIONS ON THE HABIT OF SMELLING.
We might very naturally suppose from the fact of the horse's applying his nose to everything new to him, that he always does so for the purpose of smelling these objects. But I believe that it is as much or more for the purpose of feeling, and that he makes use of his nose, or muzzle (as it is sometimes called), as we would of our hands; because it is the only organ by which he can touch or feel anything with much susceptibility.
I believe that he invariably makes use of the four senses, seeing, hearing, smelling, and feeling, in all of his examinations, of which the sense of feeling is, perhaps, the most important. And I think that, in the experiment with the robe, his gradual approach and final touch with his nose was as much for the purpose of feeling as anything else, his sense of smell being so keen that it would not be necessary for him to touch his nose against anything in order to get the proper scent; for it is said that a horse can smell a man at the distance of a mile. And if the scent of the robe was all that was necessary he could get that several rods off. But we know from experience, that if a horse sees and smells a robe a short distance from him he is very much frightened (unless he is used to it) until he touches or feels it with his nose; which is a positive proof that feeling is the controlling sense in this case.