mino with another having the same number of eyes. We are
therefore inclined to believe that this dog continually received
signs from its master. These signs probably were visual, perhaps
also auditory, and they were by no means involuntary. For in a book
on the training of animals, which Leonard, the owner of the dogs,
has published, and in which he describes minutely the method by
which they had been trained in their various accomplishments, he
does not mention with so much as a syllable the game of dominoes, a
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