The most significant of all Caodaist imagery is that of the Great Divine Eye / Thien Nhan. The Divine Eye became the main worshipping symbol of the Religion after His Holiness Ngo Van Chieu, the first CaoDai Disciple, saw it in a vision at Phu Quoc (a small island in the Gulf of Siam) in 1919. This Eye is a feature of the facade of the Great Divine Temple, of the windows along the Cuu-Trung-Dai and upon the great sphere of the altar it gazes out at all the worshippers and the community. The Divine Eye is also represented above the home altars of Caodaists, and so in spirit and in pictorial representation it is seen throughout (and sees) the entire Caodaist community.
The Eye is a universally potent symbol of the divine. The Eye sees and it knows, because it knows it is able to both protect us and check upon us. The Divine Eye is representative of the all-knowing attributes of Duc Cao Dai / God the Father. Many tourists liken the presence of the eye symbol to something similar found on the American one-dollar bill (a symbol that can be traced back to Masonic imagery), however the mystic and universal symbolism of the Divine Eye extends throughout the religious history of the world. For the ancient Egyptians there was the eye of Horus; for the Hindus the third eye of Siva (Shiva); and for the Norse the single eye of Odin. All of these symbolised omniscient and divine attributes. As the Encyclopedia of Religions (ed; Micea Eliade) explains, "The Indo-European world attached the same value to the eye as to the sun and to the gods, that is, the quality of being able to see everything." (vol 5 page 237) The Buddha is said to have received inner enlightenment through the celestial eye and this "permitted him to see the life of all beings simultaneously and gave him knowledge of the chain of the fundamental forces of existence." The Divine Eye throughout history is also there to remind us that as God watches us, so too must we keep watch over ourselves in order to follow the ways of heaven.
In addition the Divine Eye or the All Seeing Eye of God in the Cao-Dai Temples is normally formed within a triangle, and serves to remind the Cao-Dai believers that the Supreme Being/God witnesses everything, everywhere, all the time.
God the Father taught us to symbolize Him by the Eye. It is the image of universal and individual consciousness.
" The eye is the master of the heart /
(Nhan thi chu tam)
Two sources of pure light (Yin and Yang) are their master; / (Luong quang chu te)
Light is the spirit, / (Quang thi than)
The spirit itself is God, / (Than thi Thien)
God is Me. / (Thien gia nga gia)"