thing which he certainly would have dwelt upon, if he had believed in the animals' power of independent thought. He would not have remained silent concerning this greatest--though only apparent--achievement of his educational endeavors. But his whole book is evidence that he was too wise to have thus deceived himself, and our only alternative is to believe that he was playing a joke on his credulous admirers.] [Footnote AO: P. Wasmann, S. J. in the third edition of his book, "Instinkt und Intelligenz im Tierreich" (Freiburg, Herder, 1905), discusses the case of Hans and quotes from a letter I wrote him concerning the matter. In the quotation an error has crept in, which I would here correct. The statement is ascribed to me that "Hans differs from other horses only in his extraordinary power of observation, an unintentional by-product of intentional training," whereas in my letter I said: "unintentional by-product of intentional education."] This self-deception is easily understood when we consider the two predominent characteristics of the man: the pedantry of the pedagogue, and his proneness to be possessed by a single idea, which is a peculiarity of those of an inventive turn of mind. Adhering closely to a preformed plan, he carefully and narrowly circumscribed the scope and order of instruction. He would not go on to the number 5 if he were not thoroughly convinced that the 4 had been completely mastered, nor would he go on to a more difficult problem in multiplication, until he felt certain that Hans was entirely proficient in the problems of the simpler sort. If he had ever put a question to Hans before its regular order, he would have discovered, to his amazement, that there really existed no difficulties for Hans, and also that the horse really required no appreciable time to acquire new material. Mr. von Osten would have had a like experience if he had asked Hans concerning the value of Chinese coins or the logarithm of 1000. However, he never did anything of the kind, but always adhered closely to his plan. He required the questioner to say: "2 and 2", and never "2 plus 2". Nor were capitals or Latin script to be used in the written material. And if upon request he did so, he did it, without faith in the result, and hence there was failure. And so he declared that "if you use Latin script Hans becomes confused and will be out of sorts for several weeks thereafter." Mr. von Osten is, and ever will remain, the schoolmaster, and will never become the psychologist, the "soul-vivisectionist". Who would work a child with such puzzling questions? and Hans was to him like a child. Thus the old man believed himself to be a witness of a continuous, organic development of the animal soul--a development which in reality had no other existence than in his own imagination.