Rabbi Shimon was in the secret of Da’at, which is the root of the central column. Da’at unites the right and the left columns of Zeir Anpin, as well as the light that spreads down to Malchut, which is the Shechina also known as the Radiation of the Heavens.
The lights that are revealed in Malchut, in the lower Garden of Eden, and all the levels above receive from this light because it is parallel to lowers and uppers realms.
The Shechina is called Radiation of the Heavens for this reason.
The ground of the Garden of Eden is closed and sealed. No light comes to it from Malchut, which is its parallel aspect. Da’at is the revelation of light between Zeir Anpin and Malchut below, and Chokmah and Binah (Father and Mother) above.
מקור הקטע: הקדמת תיקוני הזוהר עם פרוש מעלות הסולם (רבי יהודה צבי ברנדויין זל) פסקה 275