The Names of Scale Degrees and Their Meaning
By Dr. Orlando A. Mansfield
The tonic is so called because it is the first and strongest degree of the scale; the dominant (5th), because the most influential note in harmony and chord construction; the median (3rd), because midway between the tonic and dominant; the leading note (7th), because leading up to, and generally followed by, the tonic; and the super-tonic (2nd), because the next degree above the tonic. As super is the Latin prefix for above, and sub the Latin prefix for below, many students have fondly imagined that subdominant must mean “below the dominant.” This might be, as the subdominant, or 4th degree, is certainly one degree below the dominant or 5th degree. But this interpretation could not possibly apply to the submediant, or 6th degree, as this is obviously not the next degree below the mediant.
Another explanation must be found. It is this: subdominant really means (an under dominant,” a dominant below the tonic, a degree the same distance below the upper tonic that the real dominant is above the lower tonic. Hence, the dominant being five degrees above the tonic, the sub-dominant will be five degrees below. This, in the key of C, G will be the dominant, because five degrees above C, the tonic, while F will be the sub-dominant because five degrees below the tonic, C. Similarly the submediant is really “an under mediant,” below the tonic, a degree the same distance below the upper tonic that the real median is above the lower tonic, i.e., three degrees. Hence, while E is the median in the key of C, three degrees above C, the submediant will be A, three degrees below C.
Another interesting fact is that while tonic, mediant an dominant (1, 3 and 5) form the triad on, or the common chord of, the tonic, the subdominant, sub-mediant and upper tonic (4, 6, and 8) form the triad on, or the common chord of, the subdominant. Thus, in the key of C, the tonic triad will be C, E, and G, and the dominant triad G, B, and D; while the subdominant triad will be F, A, and C, these three triads between them containing all the notes of the scale of C.
The key of the subdominant is often chosen for the second movement of a sonata when the first movement is in a major key, e.g., the Largo, in D, from Beethoven’s Sonata in A, Op. 2, No. 2. Also when the first movement is in a minor key, the submediant is the tonic of the so-called “relative” minor, the minor key which possesses the same signature as the given major.
Much more could be said about the subdominant and the submediant triads and modulation to these keys, but this paper in intended to remove a difficulty or a misunderstanding and not to perpetrate a treatise on harmony or composition. And having solved one difficulty the serious student should wrestle with others, remembering the words of Terence (B.C. 105-159) which translated, signify that “there is nothing so difficult but that it may be found out by seeking.”