It is easy to explain the musical accomplishments. The tones which were played for the horse, were known to Mr. von Osten, since he himself played the harmonica, or when someone else played it, he, Mr. von Osten, could see the stoppers. He then thought of the number which indicated the tone in question, and Hans would tap it. Thus arose the tale of the horse's absolute tonal memory. This tale gained much support at the time, from an experience which has been recounted to me by the well-known composer, Professor Max Schillings. It shows more clearly than any other report how very confused were the threads that had been spun in the whole matter. In order to test the horse's musical ability Prof. Schillings played, let us say, three tones upon the accustomed instrument. Complying with Mr. von Osten's wish, Prof. Schillings always indicated which three he was about to play. The horse always tapped them correctly. In order to make a decisive test, Prof. Schillings then played, without anyone's knowledge, a note that was in reality a third below the one he had indicated to Mr. von Osten. Curiously enough, Hans tapped, as a matter of fact, the number indicating the note that was actually struck, and it was only in the third repetition and after many exhortations on the part of the master "to have a care", that the horse finally tapped the number indicating the note Mr. von Osten had in mind and which in truth was the wrong one. This curious experiment seemed to those to whom Professor Schillings communicated it, to yield conclusive evidence of the horse's absolute hearing. As a matter of fact, however, Prof. Schillings had unwittingly, and, contrary to any intention on his part, inspired the horse. Standing, as he did, just behind the right shoulder of the horse, he was able to interrupt Hans (who had begun to tap in response to a move on the part of Mr. von Osten,) by means of an involuntary movement which did the work of a closing signal. At the same time Mr. von Osten, likewise standing to the right of the horse and expecting more taps, remained perfectly quiet. (This is as it was in the tests, mentioned on page 71, in which, of two experimenters, one started the horse tapping, and the other stopped him.) Mr. von Osten very probably lost patience after Hans had seemingly given the wrong response twice, and thereupon came nearer to the horse and thus by monopolizing its attention--so as to exclude Prof. Schillings--he was able to get the response so ardently desired.[AF] When, in tests such as these, two stoppers were opened and thus two notes sounded, Mr. von Osten would count the number of stoppers intervening between the two, and Hans would tap the number. And so arose the tale of Hans's knowledge of musical intervals. Whenever the two notes were sung or whistled, in which case there would be no stoppers that could be counted, then Mr. von Osten, who was quite destitute of musical knowledge, was at a loss, and also Hans.