The error of the Pythagoreans, it may be pointed out, did not lie in the misuse of experimental data, but in the philosophical deductions therefrom. To the followers of Pythagoras a harmonic consonance was not a perception, it was a thing the existence of which could be conceived independently, a thing as real as the string which had given it birth. Sound was to them, therefore, a distinct identity, possessing attributes pertaining only to itself, yet susceptible of impression from without; it was a number realized and concrete, a number simple and all-inclusive, but, above all, a series of numbers possessing a personality, the veiling power of which both illumined and obscured a myriad symbolisms. Strict Harmonic Consonance was the utmost of numerical potency, it was a divine thought, not embodied Being. How deeply this was felt to be a truth by the Pythagoreans is evidenced by the story told of the death of Pythagoras, when the great philosopher, turning to his disciples, gave as his last instruction “Always the monochord!” As for the value of the Pythagorean school as a whole, it is manifest that it must be considered as a group of mystical speculators, professing to be students of music and claiming Pythagoras as their master, but, in actual verity, doing little more than reducing sounds to air vibrations and ascertaining the numerical relations of pitch. Lovers of music they were not, they were mathematical precisians, perceiving no beauty and hearing no inspiration in melodic sounds except in such wise as these fitted into an ordered sequence of arithmetical form. The development of the Pythagorean school was rendered all the more self-centred by the vitality and strength of the Empiricists. This flourishing school of musical art was concerned with arbitrary regulations as to the most acceptable forms of composition. The Empiricists determined what melodies were suitable to certain instruments. They debarred the flute from certain festivals and admitted it to others, they decided upon the forms of construction of musical instruments, and, above all, they insisted upon the performance of certain compositions in the traditional style. While not avowedly hostile to the Pythagoreans, the Empirical school paid little heed to the mathematical speculations of the learned, and song and dance continued because music was an art. Great as was the symbolic majesty of the Monochord, the surging strain of the lyre meant infinitely more to the life of Ancient Greece. The second great development of Greek musical philosophy is that of Aristoxenus (b. 354 B. C.), whose systemization of the transposition scales has already been mentioned. If Pythagoras established some of the fundamental rules of acoustics, Aristoxenus may be given the credit of establishing Musical Science; the former was a branch of a science, the second was the science of an art.