>>24572322 (OP)It's simple, really. The triad represents perfection. One comes into being, then creates Two. To prevent stagnation and eternal conflict, Three manifests from One and Two to birth a new harmony. The triad is within the human brain (Id, Ego, Super-Ego) and the world (the heavens, the earth, and the ocean).
The triad is seen all throughout human culture: the three jewels of the Buddha, the Trikaya, the Trimurti, the Christian Trinity, the Three Pure Ones, the triple-headed goddess motif, the Three Sacred Treasures, the three beasts of the Bible, etc.