Plutarch, De Iside et Osiride
Frank Cole Babbitt, Ed.

The better and more divine nature consists of three parts : the conceptual, the material, and that which is formed from these, which the Greeks call the world. Plato¹ is wont to give to the conceptual the name of idea, example, or father, and to the material the name of mother or nurse, or seat and place of generation, and to that which results from both the name of offspring or generation.

One might conjecture that the Egyptians hold in high honour the most beautiful of the triangles,² since they liken the nature of the Universe most closely to it, as Plato in the Republic ³ seems to have made use of it in formulating his figure of marriage. This triangle has its upright of three units, its base of four, and its hypotenuse of five, whose power is equal to that of the other two sides.⁴ The upright, therefore, may be likened to the male, the base to the female, and the hypotenuse to the child of both, and so Osiris may be regarded as the origin, Isis as the recipient, and Horus as perfected result. Three is the first perfect odd number : four is a square whose side is the even number two ; but five is in some ways like to its father, and in some wrays like to its mother, being [p. 137] made up of three and two.⁵ And panta (all) is a derivative of pente (five), and they speak of counting as ‘numbering by fives.’ ⁶ Five makes a square of itself, as many as the letters of the Egyptian alphabet, and as many as the years of the life of the Apis.

Horus they are wont to call also Min, which means ‘seen’ ; for the world is something perceptible and visible, and Isis is sometimes called Muth, and again Athyri or Methyer. By the first of these names they signify ‘mother,’ by the second the mundane house of Horus, the place and receptacle of generation, as Plato⁷ has it, and the third is compounded of ‘full’ and ‘cause’ ; for the material of the world is full, and is associated with the good and pure and orderly.