By addition thus: two and three make five, four and nine make thirteen, eight and twenty-seven make thirty-five. Of all which numbers the Pythagoreans called five the nourisher, that is to say, the breeding or fostering sound, believing a fifth to be the first of all the intervals of tones which could be sounded. But as for thirteen, they called it the remainder, despairing, as Plato himself did, of being ever able to divide a tone into equal parts. Then five and thirty they named harmony, as consisting of the two cubes eight and twenty-seven, the first that rise from an odd and an even number, as also of the four numbers, six, eight, nine, and twelve, comprehending both harmonical and arithmetical proportion. Which nevertheless will be more conspicuous, being made out in a scheme to the eye. Admit a right-angled parallelogram, A B C D, the lesser side of which A B consists of five, the longer side A C contains seven squares. Let the lesser division be unequally divided into two and three squares, marked by E; and the larger division in two unequal divisions more of three and four squares, marked by F. Thus A E F G comprehends six, E B G I nine, F G C H eight, and G I H D twelve. By this means the whole parallelogram, containing thirty-five little square areas, comprehends all the proportions of the first concords of music in the number of these little squares. For six is exceeded by eight in a sesquiterce proportion (3:4), wherein the diatessaron is comprehended. And six is exceeded by nine in a sesquialter proportion (2:3), wherein also is included the fifth. Six is exceeded by twelve in duple proportion (1:2), containing the octave; and then lastly, there is the sesquioctave proportion of a tone in eight to nine. And therefore they call that number which comprehends all these proportions harmony. This number is 35, which being multiplied by 6, the product is 210, which is the number of days, they say, which brings those infants to perfection that are born at the seventh month’s end.