With the introduction of the seventh interval a new era began. It would be a grave error to believe that the rules were overturned, for, instead, new principles were added to old ones as new conditions demanded. They learned how to modulate, how to transpose from one key to the next key and finally to the keys farthest away. In his treatise on harmony Fetis studied this evolution in a masterly manner. Unfortunately his scholarship was not combined with deep musical feeling. For example, he saw faults in Mozart and Beethoven where there are only beauties, and beauties which even an ignorant listener--if he is naturally musical--will see without trouble. He did not understand the vast difference between the unlettered person who commits a solecism and Pascal, the inventor of a new syntax. However that may be, Fetis gave us a comprehensive review in broad outlines of musical evolution down to what he justly called the "omnitonic system," which Richard Wagner has achieved since. "Beyond that," he said, "I can see nothing more." He did not foresee the a-tonic system, but that is what we have come to. There is no longer any question of adding to the old rules new principles which are the natural expression of time and experience, but simply of casting aside all rules and every restraint. "Everyone ought to make his own rules. Music is free and unlimited in its liberty of expression. There are no perfect chords, dissonant chords or false chords. All aggregations of notes are legitimate." That is called, and they believe it, the _development of taste_. He whose taste is developed by this system is not like the man who by tasting a wine can tell you its age and its vineyard, but he is rather like the fellow who with perfect indifference gulps down good or bad wine, brandy or whiskey, and prefers that which burns his gullet the most. The man who gets his work hung in the Salon is not the one who puts on his canvas delicate touches in harmonious tones, but he who juxtaposes vermillion and Veronese green. The man with a "developed taste" is not the one who knows how to get new and unexpected results by passing from one key to another, as the great Richard did in _Die Meistersinger_, but rather the man who abandons all keys and piles up dissonances which he neither introduces nor concludes and who, as a result, grunts his way through music as a pig through a flower garden. Possibly they may go farther still. There seems to be no reason why they should linger on the way to untrammeled freedom or restrict themselves within a scale. The boundless empire of sound is at their disposal and let them profit by it. That is what dogs do when they bay at the moon, cats when they meow, and the birds when they sing. A German has written a book to prove that the birds sing false. Of course he is wrong for they do not sing false. If they did, their song would not sound agreeable to us. They sing outside of scales and it is delightful, but that is not man-made art.