E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Odd Numbers. Numero Deus impare gaudet (Virgil: Eclogues, viii. 75). Three indicates the beginning, middle, and end. The Godhead has three persons; so in classic mythology Hecate had threefold power; Joves symbol was a triple thunderbolt, Neptunes a sea-trident, Plutos a three-headed dog; the Fates were three, the Furies three, the Graces three, the Horæ three; the Muses three - times - three. There are seven notes, nine planets, nine orders of angels, seven days a week, thirteen lunar months, or 365 days a year, etc.; five senses, five fingers on the hand and toes on the foot, five vowels, five continents, etc. etc. A volume might be filled with illustrations of the saying that the gods delight in odd numbers. (See ODD, NINE.)