The hypothesis that motion can only be effected mechanically, by pressure or traction or contact of some kind, is an utterly helpless one to explain even familiar movements. Gravitation itself, the grandest and most prevailing phenomenon of the material universe, has set all genius at defiance when attempting to conceive a mechanism which might account for it. The law of sympathetic association, or sympathetic assimilation, between two or more atoms, or masses of atoms, explains this grand phenomenon; but Roscoe, in theorizing on the atomic theory, says that from purely chemical considerations it appears unlikely the existence of atoms will ever be proved. It never could have been proved by mechanical physics nor by chemistry. The law which locks the atoms together would have remained an unknown law, had not Keely opened the door leading into one of nature's domains which was never entered before, unless by the fabled Orpheus, who, mythology tells us, was killed because he revealed to man what the gods wished to conceal. Certainly, whether Orpheus ever existed or not, the principle which Pythagoras promulgated as the teaching of Orpheus is disclosed in one of Keely's discoveries. In the great fresco of the school of Athens, by Raphael, Pythagoras is represented as explaining to his pupils his theory that the same principle underlies the harmonies of music and the motion of heavenly bodies. One of these pupils holds in his hand a tablet, shaped like a zither, on which are inscribed the Greek words, Diapason, Diapente, Diatessaron. Of the diapason, or concord of all, Spenser writes, in The Faerie Queen:-- Nine was the circle set in heaven's place, All which compacted made a goodly diapase. Here we have a clue to the Thirds, Sixths and Ninths of Keely's theories, in the operation of his polar negative attractor. The conception of the Pythagoreans of music, as the principle of the creation's order, and the mainstay and supporter of the material world, is strictly in accordance with the marvellous truths which are now being unfolded to science. Rightly divined Browning when he wrote of ... music's mystery, which mind fails To fathom; its solution no mere clue;