Plutarch Quaestiones Convivales 9.14.2

[2] Then said Ammonius to Herod: We have no reason to be angry with you for grasping all the Muses, since the goods that friends have are common, and Jove hath begotten a great many Muses, that every man may be plentifully supplied; for we do not all need skill in hunting, military arts, navigation, or any mechanical trades; but learning and instruction is necessary for every one that And therefore Jove made but one Minerva, one Diana, one Vulcan, but many Muses. But why there should be nine, and no more nor less, pray acquaint us; for you, so great a lover of, and so well acquainted with, the Muses, must certainly have considered this matter. What difficulty is there in that? replied Herod. The number nine is in every body’s mouth, as being the first square of the first odd number; and as doubly odd, since it may be divided into three equal odd numbers. Ammonius with a smile subjoined: Boldly said; and pray add, that this number is composed of the first two cubes, one and eight, and according to another composition of two triangles, three and six, each of which is itself perfect. But why should this belong to Muses more than any other of the Gods? For we have nine Muses, but not nine Cereses, nine Minervas or Dianas. For I do not believe you take it for a good argument, that the Muses must be so many, because their mother’s name (Mnemosyne) consists of just so many letters. Herod smiling, and every body being silent, Ammonius desired our opinions.