Professor Plumptre supposes the Urim to have been a clear and colorless
stone set in the breastplate of the high priest as a symbol of light,
answering to the mystic scarab in the pectoral plate of the ancient
Egyptian priests, and that the Thummim was an image corresponding to
that worn by the priestly judges of Egypt as a symbol of truth and
purity of motive. By gazing steadfastly on these, he may have been
thrown into a mysterious, half ecstatic state, akin to hypnotism, in
which he lost all personal consciousness, and received a spiritual
illumination and insight.