The mind that could conceive the world as a sphere and that interested itself in weights and measures was, obviously, a mind of the visualizing type. It is characteristic of this type of mind to be interested in the tangibilities of geometry, hence it is not surprising to be told that Pythagoras "carried that science to perfection." The most famous discovery of Pythagoras in this field was that the square of the hypotenuse of a right-angled triangle is equal to the squares of the other sides of the triangle. We have already noted the fable that his enthusiasm over this discovery led him to sacrifice a hecatomb. Doubtless the story is apocryphal, but doubtless, also, it expresses the truth as to the fervid joy with which the philosopher must have contemplated the results of his creative imagination. No line alleged to have been written by Pythagoras has come down to us. We are told that he refrained from publishing his doctrines, except by word of mouth. "The Lucanians and the Peucetians, and the Messapians and the Romans," we are assured, "flocked around him, coming with eagerness to hear his discourses; no fewer than six hundred came to him every night; and if any one of them had ever been permitted to see the master, they wrote of it to their friends as if they had gained some great advantage." Nevertheless, we are assured that until the time of Philolaus no doctrines of Pythagoras were ever published, to which statement it is added that "when the three celebrated books were published, Plato wrote to have them purchased for him for a hundred minas."(2) But if such books existed, they are lost to the modern world, and we are obliged to accept the assertions of relatively late writers as to the theories of the great Crotonian. Perhaps we cannot do better than quote at length from an important summary of the remaining doctrines of Pythagoras, which Diogenes himself quoted from the work of a predecessor.(3) Despite its somewhat inchoate character, this summary is a most remarkable one, as a brief analysis of its contents will show. It should be explained that Alexander (whose work is now lost) is said to have found these dogmas set down in the commentaries of Pythagoras. If this assertion be accepted, we are brought one step nearer the philosopher himself. The summary is as follows: