Between simple intervals there is little difficulty in deciding whether the second note must rise or fall. And in regard to phrases, or sections of a phrase, if we analyse their structure and follow out their harmonic tendency, their resolution is equally clear. But this sense of destination may be provoked in each part by different intervals. As we have observed already, every one of the four parts must flow melodically and freely. But to secure that result it will be necessary to introduce between the notes which begin a phrase and establish its general atmosphere other notes which often are not consonant with those employed in the other parts and whose incidence is governed by the accent. This is what we call a transitus regularis et irregularis.(144) Each part starts from a fixed point, and returns to it, but travels freely between them. No one has made more use of such progressions than Bach in order to colour his parts and give them a characteristic melodic line. Hence, unless his music is played with perfect fluency, occasional passages will sound harshly and we may be tempted to accuse him of exaggeration. But the charge is ill founded. Once we play them as Bach intended them, such passages reveal their full beauty and their attractive though bizarre dissonance opens up new vistas in the realm of sound. But, to speak in detail of Bach’s transgression of recognised rules. To begin with, he admitted octaves and fifths provided they sounded well; that is, when the cause of their being forbidden did not arise.(145) Everybody knows that there are positions in which they sound well, and others when they should be avoided, owing to the harsh effect or thin harmony they produce. Bach’s octaves and fifths never produce bad or thin harmony, and he was very definite as to when they could and could not be used. In certain circumstances he would not permit hidden fifths and octaves even between the middle parts, though we exclude them only between the outer parts. Yet, on occasion he used them in such a barefaced manner as to puzzle the beginner in composition. But their use very soon commends itself. Even in the last revision of his early compositions we find him altering passages, which at first sight appear impeccable, with the object of enriching their harmony and without scrupling to use hidden octaves. A remarkable instance occurs in the first part of the _Well-tempered Clavier,_ in the E major Fugue, between the fifth and fourth bars from the end.(146) I regret to this hour that, on looking over the later text, from which Hoffmeister and Kühnel’s edition of that work is printed,(147) I was so foolish as to reject Bach’s amended reading there, merely because the harmony is unorthodox though more pleasing. I stupidly preferred the older, more correct, and harsher reading, though in the later text the three parts run easily and smoothly. And what more can one demand?