V 



308 LECTURE XXXIII. 



the neighbouring notes on either side, with the addition of fiTe<^tni js 



or flat, accordingly as they are a semitone higher or lower than the notes 



of which they bear the names. 



For still further variety, we sometimes change the place of the middle 

 note of each triad, placing the minor third, or the interval expressed by the 

 ratio of 5 to 6, below the major, which is in the ratio of 4 to 5 ; and the 

 scale thus formed is called the scale of the minor mode, in contradistinction 

 to the major, the three principal thirds being depressed a semitone. Some- 

 times, however, the alteration is made in the third of the key note only, 

 especially in ascending, in order to retain the seventh of the major scale, 

 which leads so naturally into the -octave, as to be sometimes called the 

 characteristic semitone of the key ; and it is for this reason, that the triad, 

 in which it is found, is called the accord of the dominant, which, in all 

 regular compositions, immediately precedes the termination in the key 

 note. 



The major and minor triads, with the discord of the flat seventh, may be 

 considered as constituting the foundation of all essential harmonies. The 

 flat seventh is principally used with the major triad, in transitions from 

 the fundamental key into its fourth, to which that seventh naturally 

 belongs as a concord ; so that it serves to introduce the new key, by 

 strongly marking the particular note in which it differs from the old one ; 

 and in such cases the flat seventh always descends into, or is followed by, 

 the third of the new key, and the third of the first triad ascends into the 

 new key note. Other discords are also sometimes introduced, but they are 

 in general either partial continuations of a preceding, or anticipations of a 

 following accord. Two different parts of a harmony are never allowed, in 

 regular and serious compositions, to accompany each other in successive 

 octaves or fifths, since such a succession is found to produce a disagreeable 

 monotony of effect, except when a series of octaves is continued for some 

 time, so as to be considered as a repetition of the same part. 



These are almost the only principles upon which the art of accompani- 

 ment, as well as the general theory of practical music, is founded. Many 

 prolix treatises have been written on the subject, but they only contain 

 particular illustrations of the application of these principles, together with 

 a few refinements upon them. The art of composition, however, depends 

 much more on a good taste, formed by habitual attention to the best 

 models, and aided, perhaps, by some little natural predisposition, than 

 upon all the precepts of science, which teach us only how to avoid what is 

 faulty, without instructing us in the mode of attaining what is beautiful or 

 sublime. 



It is impossible to assign any such proportions for the twelve sounds 

 thus employed, that they may be perfectly appropriate to all the capacities 

 in which they are used ; their number is, therefore, sometimes considerably 

 increased ; and in some instruments they may be varied without limit, at 

 the performer's pleasure, as in the voice, in instruments with finger boards, 

 and in some wind instruments ; but in many cases this is impracticable, 

 nor could any imaginable alteration make all the intervals perfect, unless 

 every note were varied, whenever we returned to it by steps different from 



