Visible and invisible colors
Rabbi Elazar wonders why in the passage, "And I appeared to Abraham, to Isaac and to Jacob etc.," it says, "And I appeared" rather than "And I spoke." Rabbi Shimon explains the secret of visible and invisible colors. The patriarchs saw the visible colors of El Shadai that are the reflection of the supernal colors. Moses was the only person to be able to see the higher colors of Chesed-Gvurah-Tiferet.
Next, Rabbi Shimon turns to: "And they who are wise shall shine like the brightness of the firmament; and they who turn many to righteousness like the stars for ever and ever," saying that the 'wise' man is the kind of person who understands higher matters intuitively because they are too deep for words. He explains that there are four lights, the light that illuminates, the light that shines purple light and the light that does not illuminate. These correspond to Chesed, Gvurah, Tiferet and Malchut. The three higher lights are reflected in Malchut. We are told that there are three colors in the eye - white, red and green - which are like the three colors of Zeir Anpin. The pupil of the eye is black, the mirror that does not illuminate. Rabbi Shimon says that the secret of seeing the three concealed lights is to close your eyes and turn them inwardly toward Cholam, Shuruk and Chirik - the three places that receive love, power and beauty. When the eye is closed it sees the higher colors as did Moses, but when it is open it sees only the lower colors. This explains why Moses was spoken to by Yud Hei Vav Hei but the patriarchs were spoken to by El Shadai.
Finally, Rabbi Shimon tells us that one is not allowed to greet a wicked person, but if one greets a righteous person it is the same as though he were greeting Hashem.