From this central fact, proved over and over again without any possible doubt to be true of the "thinking" animals, there have been developed two distinct groups of consequences: (1) the prodigious mathematical performances occurring as by magic among the Elberfeld horses at a certain point of their "education": (2) the apparent manifestations of thought through the typtology or rapping out of words, culminating in the "philosophic" achievements of Rolf and Lola. For the reasons just mentioned the first group of consequences seems to me to admit largely of biological (i.e. biopsychical) explanation; however, anything which eventually does not fit into the biological explanation may be made to enter without any effort into the second method of explanation which, in view of the facts, it seems to me that we must adopt for the second of the two groups of consequences above referred to. That mathematics can be "lived" rather than "known"--or, if any one prefers the term, "realized"--by an organism which is without any psychical accompaniment whatever of the human type, is a fact which I find credible. But when Rolf speaks to me of the origin of the soul, or makes up poetry; when Lola complains to me of honour lost, etc., the thing is not credible to me in any way except by paying attention to nothing except the feeling, which is so difficult to avoid, that what is here speaking to me, versifying and complaining, is a psychical "quid," absolutely human and only human; a "quid" which therefore is (after all) not the animal's, although manifested in some way through it. The difficulty naturally consists in deciding precisely how this happens. But it does not seem to me altogether impossible to arrive at a proper hypothesis. I have already said that we must discard, because of its inability to explain a great part of the facts, the most easy and simple hypothesis--that of some mechanical signal (e.g. by means of a supposed pressure of the hand under the cardboard, or by the hand itself which is held out to the animal, in the case of the dogs which have so far been experimented with). Here we also have to remember the proposition laid down by Miss Kindermann herself that "She did not wish to let herself be carried away by sentiment," and that she would seek all possible proofs which were good logically. Having excluded the hypothesis of deceit, it is a further proof of the sheer impotency of the theory of signals, when regard is had to the available amount of the material observed and recorded in the authoress, if we ask how is it possible to imagine that she (knowing very well, as she says, the suspicion resting on the method) in a year or more of work with Lola should not herself have perceived that she herself had been producing by mechanical means the rapped answers of her pupil?