by Plato but brought to light by the musicologist, Ernest McClain [3,4,5], will be shown to be the basis of the Just scale, another ancient musical scale. I shall refer to this table as the Harmonic Matrix, or simply as HM. In his books and papers, 19-32 McClain has made a strong case for music serving as the lingua franca of classical and sacred texts, ANCIENT providing plausible explanations of otherwise too HARMONIC LAW difficult to understand passages and providing metaphors to convey ideas and meaning. In this paper I will focus primarily on the mathematics and music at the basis of ancient musical scales, Jay KAPPRAFF and this paper will serve as an introduction to the work of McClain. An original contribution of the Abstract author is a collaboration with McClain to create an The matrix arithmetic for ancient harmonic algorithm for the construction of an approximation theory is presented here for two tuning systems to 2 good to six decimal places using the musical with opposite defects: ‘Spiral fifths’ as presented scale. This approximation was used in Vedic India by Nicomachus, a Syrian Neo-Pythagorean of the with a geometric derivation. The author will also second century A.D., and Plato’s ‘Just tuning’ as demonstrate that the musical scale functions as a reconstructed by the ethnomusicologist, Ernest vector system simplifying musical computations. McClain, from clues preserved by Nicomachus 1 2 4 8 16 32 64 ... th and Boethius (6 century AD). These tables lie 3 6 12 24 48 96 ... behind the system of architectural proportions 9 18 36 72 144 ... used during the Renaissance, and their basic ratios 27 54 108 216 ... now pervade modern science as the foundation of 81 162 324 ... a ‘string theory’ formally presented first in Euclid. 243 486 ... Calculation employs an early form of a log table 729 ... governed by vectors of 2-3-4 in the first, and by Table 1. Nicomachus’ table for expansions of the ratio 3:2 3-4-5 in the second. (as relative frequency). The square root of 2 plays a central role in integrating these systems governing 12-tone theory The construction of ancient musical scales will from the perspective of four primes--2, 3, and 5 be shown to be based strongly on primes: 2, 3, 5 generate all ratios under the overview of 7— as and 7. There were no easy notations for fractions disciplined ‘self-limitation’ within a ‘balance of in ancient civilizations so the problem was to perfect opposites’. represent ratio in terms of whole numbers. To this Plato states: Introduction ‘For surely you know the ways of men who Nicomachus, writing about 150 AD, forms are clever in these things. If in the argument someone attempts to cut the one itself [i.e., one of the best links to what survived from his use a fraction], they laugh and won’t permit it. day about Greek theory of numbers and music If you try to break it up into small coin, they [1,2]. I shall describe how the sequence of integers multiply…’ Republic 525 shown in Table 1, and attributed to Nicomachus, defines perfect octaves, fifths, and fourths, the Ancient musical scales must be assumed to only consonances recognized by the Greeks, be elegant solutions in smallest integers to this and lies at the basis of ancient tuning systems problem. preserved by Ptolemy. A second table inferred Two of Plato’s foremost concerns were 20 ANCIENT HARMONIC LAW limitation, preferably self-limitation, and balance chosen as the first or fundamental, and since any of opposites. McClain states [5] that tone is perceived by the ear to be identical when ‘In political theory as in musical theory, played in different octaves, each tone of the scale both creation and the limitation of creation pose refers to a pitch class of tones differing by some a central problem. Threatening infinity must be number of octaves. contained. What musicians have shown possible in The D mode, or ancient Phrygian mode, was tones, the philosopher should learn to make the preferred self-symmetric scale of ancient possible in the life political.’ times (notice the symmetric pattern of the keys on both sides of D in figure 1), and I will represent As for the balance of opposites, in the all scales in the D mode. The heptatonic scale Republic, Plato states: beginning on C: CDEFGABC is the famous do-re- ‘Some things are apt to summon thought, mi... scale, and common reference now in Western while others are not…Apt to summon it are those that strike the sense at the [same] time as civilization. The intervals of the piano are equal- their opposites.’ tempered so that beginning on any tone, after Republic 524 twelve perfect fifths one arrives again at the same One of the themes of this paper will be to tone seven octaves above or below in pitch. show how the musical scale expresses the concepts Because of the periodicity of the chromatic of lmitation and balance of opposites. scale, it can be comfortably represented on a tone
Figure 1. The piano keyboard Our story begins with a look at the 88 keys of circle as shown in figure 2 with semitone intervals the piano shown in figure 1. Three tones, A, D, and between adjacent tones, and with pairs of G, have been highlighted. D is located at the center semitones equaling a wholetone. Each semitone of of symmetry of the black and white pattern of the equal-tempered scale is worth 100 cents now keys with G and A seven tones below and above D. assigned on a logarithmic scale with 1200 cents to The interval from D to G spans five tones DCBAG the entire octave. The relationship between cents called a falling fifth while from D to A is a rising and frequency is discussed in the appendix. The fifth (DEFGA). In the opposite direction these equal-tempered tritone located at 6 o’clock has a intervals are perfect fourths (DEFG and DCBA). relative frequency of 2. Proceeding clockwise The pattern of black and white keys repeats every around the circle leads to a rising scale while a counter-clockwise rotation leads to a falling scale. 12 tones, called the chromatic scale, with the white The numbers 0-12 on the clock positions number keys repeating every seven keys and assigned the the tones of the chromatic scale, and they can be tone names DEFGABCD’, the interval from D thought of as numbers in a mod 12 number system to D’ being called an octave, and with the black where any multiple of 12 can be added to one of # keys augmented or diminished by sharps ( ) and the integers to get another tone in the same pitch flats ( ) to insert semitones between wholetones. class. I will refer to the numbers on the face of the The white keys produce heptatonic scales in seven clock as the digital roots of the pitch class more different modes depending on the reference pitch. commonly called principal values in mathematics. The black keys naturally provide five pentatonic Notice that the digital roots of two tones modes, repeating on the sixth tone. Because of the symmetrically placed around the tone circle sum to periodicity of the musical scale, any tone can be 12. Such tonal pairs are called complementary. Jay KAPPRAFF 21
Arithmeticization of the ancient musical scale begins with the numbers 1, 2, 3, and 4. The Sliding bar reference length of a vibrating string is arbitrarily assigned the value of 1 unit which is taken to be the fundamental tone when bowed or plucked. If the length of the fundamental is multiplied or divided by any power of 2, the resulting tone sounds to the ear identical in implied harmonic function to the fundamental by some number of octaves. In other words, shortening the string by half gives Unison Fourth Fifth Octave D a tone one octave C# 0 E 11 1 higher in pitch while C E 10 2 doubling the length of Figure 3. A sliding bridge on a monochord divides the string the string results length representing the fundamental tone into segments 9 3 B F in a falling octave. corresponding to the perfect fifth (2:3) fourth (3: ) and octave Therefore each tone is (1:2). 8 4 B F# a representative of a associated with the ratio 3:1. This ratio is equivalent, 7 5 A 6 G pitch class of tones all after suppressing octave powers of 2, to relative A= # differing by a multiple string lengths 3/2 and 3/4 of a falling perfect fifth Figure 2. The Tone Circle. of 2 in string length. or a rising fourth. In this case, taking D to be the That all tones in a pitch class sound alike to the ear fundamental, 3:1 is represented by the pitch class G in harmonic function is considered to be the miracle (a fifth below D). Alternatively, 3 can be associated of music. In figure 3, if you place your finger at the with the ratio 1:3 which in turn corresponds to 2/3 point on the string and sound the string it gives relative string lengths 2/3 and 4/3, a rising perfect rise to a perfect fifth; lengthening the string by one fifth or a falling fourth, i.e., inverse ratios. Now half results in the interval of a falling fifth. If you with D as the fundamental, 3 is represented by shorten the string by one fourth a perfect fourth pitch class A. So the integer 3 represents two pitch arises. The modern concept of relative frequency classes and takes on the four inverse interpretations is reckoned as the inverse of the relative string : 3/2, 3/4, and 2/3, 4/3. Since the modern concept length. A new pitch class at the interval of a fourth of relative frequency is the inverse of relative string or fifth requires a new factor of 3. It is therefore length, the second interpretation relates to relative easy to comprehend why the musical scale served frequency. Here 3/2 and 3/4 are rising fifths and well as a metaphor for the act of creation: ‘Deity’ falling fourths respectively, while 2/3 and 4/3 are commensurate with ‘1’, doubling to 2 (the female falling fifths and rising fourths respectively. The number) as the ‘Great Mother,’ and both of these second interpretation is more familiar to musicians, adding to 3 in ‘procreation’ of a ‘male’ son. Each and I will follow it for most of this paper. These new tone in this sequence requires another factor four interpretations: rising scale, falling scale, of 3, constituting the preferred ‘Pythagorean relative string length, and relative frequency can be tuning’ of ancient Greece. confusing to someone trying to orient themselves with regards to interpreting the musical scale in 2. The Tetrapolarity of the Ancient Musical Scale. terms of integers. How does a new pitch class emerge from the The situation is analogous to the paradox of number 3? It can do this in two ways: by relative the relative motion of a pair of railway trains. The string length or relative frequency. Let’s first question one asks is: am I moving forward and consider relative string length. In the ancient world, the other train stationary, or am I stationary and lacking the concept of a fraction, the integer 3 had the other train moving backwards? This paradox four musical interpretations. First of all, 3 can be is then made more confusing by witnessing it in 22 ANCIENT HARMONIC LAW a mirror in which forward and backwards reverse leading to the tetrapolarity: moving-stationary, and forward-backward. 6/12 3. The Greek scale. In row 2 the three tones are represented in their Placing into the 2:1 octave, the fundamental D respective pitch classes. In row 3, multiplication by (1), octave D’ (2), fifth A (3/2) and fourth G (4/3) 3 eliminates fractions. When the terms in column in scale order and using relative frequency gives the 3 are multiplied by powers of 2, the three integers rising scale: of row 4 are obtained which duplicates column 3 of Table 1. When the fundamental is doubled to 12 in order to enclose or ‘seal’ the largest integer, 9, in 4/3 3/2 the 6/12 octave, the twin tones multiply by powers Multiplying by the common denominator, 6, of 2 to 8 and 9, with ratio 9:8, without changing results in the integer scale: pitch class. Rearranging the integers of row 5 in scale order we have again: A and G reverse when relative string length is used instead of relative frequency. Notice that This is read as a rising scale from left to right these ratios are represented in Table 1 with the or a falling scale from right to left. Again, rising and integers along each row expressing the ratio 1:2, falling, and A and G reverse when considering the the columns 2:3, and the right leaning diagonals numbers to be relative string length. Greek musical :3. These rising fifths and fourths differ inaudibly theory was founded on this formula. Observe from in pitch from the piano fifths and fourths described Sequence 2 that for the twin tones, A functions as above. In fact, equal-tempered relative frequencies the arithmetic mean of the octave DD’ while G of A and G are 700 cents and 500 cents, is the harmonic mean, reversing when the integers respectively, while corresponding 3:2 and 4:3 ratios, represent relative string length. The integer 9 is the are 702 cents and 498 cents, respectively, slightly arithmetic mean of 6 and 12 because, 9-6 = 12-9 overshooting and undershooting. This extremely whereas, 8 is the harmonic mean because: 8-6/6 = small discrepancy between tonal values is referred 2- 2. Plato gave great significance to the Greek to in musical theory as a comma. otice in figure formula when he stated: 2 that the twin tones G and A occupy symmetric positions on the tone circle as do any pair of tones ‘…In the potency of the mean between these terms (6,12), with its double sense, we with reciprocal ratios. In this case, the symmetry have a gift from the blessed choir of the Muses is the result of the geometric sequence : 1/3, 1, 3 to which mankind owes the boon of the play in which D as 1 is the geometric mean of AG as 3 of consonance and measure, with all they contribute to rhythm and melody.’ and 1/3 respectively following harmonic law which states that as relative frequencies multiply, intervals [Epinomis 991] add, i.e., 3 x 1/3 = 1 whereas 7 + 5 = 12. Also it seemed significant that the fundamental In an alternative representation, let’s derive is 6, a perfect number, i.e. the sum of its factors 1, the twin tones A and G from the middle at the 2, 3 regarding which Plato states: fundamental D by moving along the tone circle 7 ‘...for a divine birth there is a period semitones in a clockwise direction from D to A comprehended by a perfect number.’ and 7 counterclockwise semitones from D to G. A [Republic 546] and G lies in the pitch classes: 3:1(A) and 1:3 (G).