13. Kindred to this is the triad; equally indivisible and perfect, the first of those sums which are formed of even and uneven numbers. For the perfect number two, receiving the addition of the unit, forms the triad, the first perfect compound number. And the triad, by explaining what equality is, first taught men justice, having itself an equal beginning, and middle, and end. And it is also an image of the mysterious, most holy, and royal Trinity, which, though itself without beginning or origin, yet contains the germs, the reasons, and causes of the existence of all created things.