TRIADS, groups or sets of three persons, things, or attributes, are found in many concepts of the divine. Because triads involve an uneven number they have been considered to be perfect expressions of unity and proportion, corresponding to a threefold division in nature or to images of the nuclear family.

In Indian mythology, the Ṛgveda suggests a threefold classification of its many divinities into gods of heaven, air, and earth. In its prayers three chief gods represent the powers of these natural elements: "May Sūrya [sun] protect us from the sky, Vāta [wind] from the air, Agni [fire] from the earthly regions" (10.158.1). Agni, god of fire and messenger to the gods during fire sacrifice, took three forms, as the sun in the sky, lightning in the aerial waters, and fire on earth. Commentators on the Vedas considered that the number of gods could be reduced to...