Whenever someone has been graced to perceive the Ultimate Reality, the Highest, the One, it is because their consciousness has been transfigured into that of God’s consciousness, such that they look out through God’s eyes onto God. The 13-14th century Christian mystic Meister Eckhart put it this way,
The eye wherein I see God is the same eye wherein God sees me: my eye and God’s eye are one eye, one vision, one knowing, one love.
What does that mean? I think it means that they are not seeing as we usually see. It is not a typical ordinary seeing from our natural eyes with our ordinary rational mind. It is an alteration of consciousness, a change of mind (metanoia), a transfiguration of consciousness, a shift from our typical way of knowing to an entirely different way of knowing and perceiving. It is intuitive and direct experience, not logical, rational, or intellectual. It is subject to Subject, not subject to object. The Subject comes to know itself.
This is why some texts say that no human has ever seen God, that no flesh can witness God and live (Exodus 33:20; Moses 1:5, 11; D&C 58:3; 67:10-13; 84:22). Some texts say that people die if they see God (Judges 13:22; Moses 1:11). Indeed, they do “die.” Seeing God is a death of “self.” They have put off their “natural man” (Mosiah 3:19), their attachment to their flesh-body and “carnal mind,” their ego-self identification, they’ve suffered an ego death, an anatta or anatman (no-self) experience as the Buddhists say, the fana annihilation of “self” as the Sufis say, the moksha liberation as the Hindus say, the korban sacrifice of ego as in Judaism, they are crucified as the Christian mystics say, and become One with the ground of Being, their fundamental essence, which is God. They have realized their Oneness with the “Only Begotten Son,” “which is in the bosom of the Father” and sees the Father (John 1:18), the Only Created Creation of the Source of the Universe sees its own Source. They have been “resurrected” in Christ consciousness and see God at-one in them as Jesus saw the Father at-one in him. They see God in God.
The human doesn’t see God. God sees himself.
The Mormon prophet Joseph Smith once described how his seer stone worked:
With some labor and exertion he found the stone, carried it to the creek, washed and wiped it dry, sat down on the bank, placed it in his hat, and discovered that time, place and distance were annihilated; that all intervening obstacles were removed, and that he possessed one of the attributes of Deity, an All-Seeing-Eye.
I believe Joseph used his seer stones to shift his consciousness, his mode of conscious perception, not unlike how many meditators use a meditation object of some kind to change their consciousness, in order to see as God sees, and I think this is the same as every person who has ever seen or known the Divine, the Transcendent, the Eternal. It involves either a willed or spontaneous transfiguration of consciousness where the ego-self falls away, and one sees from the Oneness or Nonduality of Being, which many call “God.”
(The photo above is of the All-Seeing Eye symbol as found on the Salt Lake Temple of the LDS Church.)