Commenting on Joyce’s Ulysses, Joseph Campbell identifies what he calls ‘the mystic realisation’. It is the mystery of non-duality that runs so counter to our everyday perception but rings so true in the depths of the silent heart.
Says Campbell: “Stephen, strolling along the shore, is thinking of the relationship of visible things to their source—of a son to a father, of Hamlet to Shakespeare, of himself to the ground of his being—and he comes to the relationship of Jesus, the Son, to God the Father, which is a Christian problem. If Jesus is God, and his Father is God also, what then is the relationship? Jesus said, “I and my Father are one,” and those words brought him to the cross. Sufi mystic al-Hallaj said the same thing, “I and my Beloved are one,” and he too was crucified. This is the mystic realization: you and that divine immortal being of beings of which you are a particle, are one. The classical statement of the idea is “tat tvam asi,” “you are that,” and the famous formula in the Chāndogya Upanishad: “you are yourself the divine mystery you wish to know.” “I and my father are one.”
From Joseph Campbell, Mythic Worlds, Modern Words, p.71