Almost immediately after Euripides, appeared the great comedy writer, Aristophanes, about 420 B.C. This great artist was not simply a dramatist, but also a patriot and a philosopher. In several of his plays he satirizes the classical dramas effectively, parodies their effects, and in general pokes fun at them. He was, however, a well accomplished musician, who might, if he had chosen, have gone on in the steps of his predecessors. But the times were not favorable to this. Previous to the time of Socrates, orators in addressing popular assemblies, lawyers in pleading cases, and all public speakers, appear to have made use of the cithara as a sort of accompaniment, if for no other purpose than to assure themselves of securing a proper pitch of the voice. But Socrates drew attention to verbal distinctions, made words the image of exact concepts, and in general set in operation an era of scientific classification and purely intellectual development, into which music could not enter, especially in a form so poor upon the tonal side as Greek art then was, and always remained. Then came the great orators, of whom Demosthenes was the greatest, who seems to have been the first to speak without musical aids; and Plato, with his philosophy; and after him the great Aristotle, the father of scientific classification and orderly knowledge. To a disciple of Aristotle, Aristoxenus, we are indebted for the first really musical work which has come down to us. It is true that the so-called Problems of Aristotle contain many of a musical character, showing that this great master observed tonal effects in a purely musical spirit, but he did not make a scientific treatise upon the art. In his Politics he has much admirable matter relating to music, and its influence upon the feelings and its office in life has hardly been better explained than by him. But music upon the practical side remained a sealed book. Among the lucid musical questions of Aristotle's Problems (which, if not by Aristotle himself, are at least the product of his time or the succeeding century) he refers to the phenomena of sympathetic resonance; he asks further, why it is that when _mese_ (the keynote of the lyre) is out of tune everything is out of tune; yet when any other string is out of tune it affects only the particular string which is not correctly adjusted. One of his most instructive, but also, as it turned out, most misleading questions was why they did not magadize (sing in) fourths and fifths as well as in octaves, since the consonances of the fourth and the fifth are almost as well sounding as those of the octave. This question appears to have led to the practice of what Hucbald called "diaphony." This question, it may be remarked incidentally, is conclusive that they did _not_ use the third as a consonance in Aristotle's time, nor sing together in fourths, fifths, or any other intervals than the octave.