The vision Ngo Van Chieu reported on Phu Quoc in 1921 was of a single large eye, radiant, appearing before him while he considered how a formless divinity might be represented at all. He asked, by the means available to him, whether some other symbol might serve, and the eye returned. He began to venerate it, and the Divine Eye, set within a triangle and surrounded by rays, became the sign under which Cao Dai worships. It is placed above the altar in every temple, and it is what a visitor to Tay Ninh sees first.
When the movement organised itself publicly in 1926 he was offered its highest office and refused it. The reasons given differ in the telling: reluctance to accept a hierarchy, disagreement with the direction of the public church, ill health. He withdrew to Can Tho in the Mekong delta and gathered a small group around a path of inward cultivation, without the elaborate liturgy, the vestments or the administration of the main body. That branch still exists, and is distinguished within Cao Dai from the large public organisation rather than opposed to it.
He died in 1932 on the river, travelling. Cao Dai reveres him as its first disciple, and the two paths he stands between, an inward discipline and a public church, remain the shape of the religion.