Plutarch De Defectu Oraculorum 36

[36] It was for this reason that among the people of olden time it was the custom to call counting numbering by fives, ¹ I think also that panta (all) is derived from pente (five) in accord with reason, inasmuch as the pentad is a composite of the first numbers. ² As a matter of fact, when the others are multiplied by other numbers, the result is a number different from themselves; but the pentad, if it be taken an even number of times, makes ten exactly; and if an odd number of times, it reproduces itself. ³ I leave out of account the fact that it is the first composite of the first two squares, unity and the tetrad ⁴ ; and that it is the first whose square is equal to the two immediately preceding it, making with them the most beautiful of the right-angled triangles ⁵ ; and it is the first to give the ratio 1 1/2: 1. ⁶ However, perhaps these matters have not much relation to the subject before us; but there is another matter more closely related, and that is the dividing power of this number, by reason of its nature, and the fact that Nature does distribute most things by fives. For example, she has allotted to ourselves five senses and five parts to the soul ⁷ : physical growth, perception, appetite, fortitude, and reason; also five fingers on each hand, and the most fertile seed when it is divided five times, for there is no record that a woman ever had more than five children together at one birth. ⁸ The Egyptians have a tradition ⁹ that Rhea gave birth to five gods, an intimation of the genesis of the five worlds from one single Matter; and in the universe the surface of the earth is divided among five zones, and the heavens by five circles, two arctic, two tropic, and the equator in the middle. Five, too, are the orbits of the planets, if the Sun and Venus and Mercury follow the same course. The organization of the world also is based on harmony, just as a tune with us is seen to depend on the five notes of the tetrachord ¹⁰ : lowest, middle, conjunct, disjunct, and highest; and the musical intervals are five: quarter-tone, semitone, tone, tone and a half, and double tone. Thus it appears that Nature takes a greater delight in making all things in fives than in making them round, as Aristotle ¹¹ has said.

[36] This is the reason why the ancients were used to express numbering or reckoning by πεμπάσασθαι, to count by fives. And I am of opinion that that word πάντα, all, is derived from πέντε, which is to say five, five being compounded of the first numbers. For all the other numbers being afterwards multiplied by others, they produce numbers different from themselves; whereas five, being multiplied by an even number, produceth a perfect ten, and multiplied by an odd number, representeth itself again; not to insist that it is composed of the two first tetragons or quadrate numbers (unity and four), and that, being the first number whose square is equivalent to the two squares before it, it composeth the fairest of right angled triangles, and is the first number which containeth the sesquilateral proportion. Perhaps all these reasons are not very pertinent to the discourse of the present dispute, it being better to allege that in this number there is a natural virtue of dividing, and that nature divideth many things by this number. For in ourselves she has placed five senses, and five parts of the soul, the vital, the sensitive, the concupiscible, the irascible, and the rational; and as many fingers on each hand; and the most fruitful seed disperseth itself but into five, for we read nowhere of a woman that brought forth more than five at a birth. And the Egyptians also tell us that the Goddess Rhea was delivered of five Gods, giving us to understand in covert terms that of the same matter were procreated five worlds. And in the universe, the earth is divided into five zones, the heaven into five circles,—two arctics, two tropics, and one equinoctial in the midst. There are five revolutions of planets or wandering stars, inasmuch as the Sun, Venus, and Mercury make but one and the same revolution. And the construction of the world consists of an harmonical measure; even as our musical chords consist of the posture of five tetrachords, ranged orderly one after another, that is to say, those called ὑπάτων, μέσων, συνημμένων, διεζευγμένων, and ὑπερβολαίων. ¹ The intervals also which are used in singing are five, diesis, semitone, tone, the tone and a half, and the double tone; so that Nature seems to delight more in making all things according to the number five, than she does in producing them in a spherical form, as Aristotle writeth.