Photo: Miriam Woelke
Without going into too many details, I am just mentioning the teaching in brief because I love it.
The Gemara in the Talmud Tractate Chullin 59b / 60a mentions a conversation between Caesar and Rabbi Yehoshua ben Chananyah.
Remark: When it says CAESAR in the Talmud, it doesn't necessarily refer to the Roman emperor but rather to a Roman governour.
Caesar asked Rabbi Yehoshua ben Chananyah to show him G - d. The Rabbi placed Caesar standing in front of the sun and asked him to look right into the bright sunlight. Caesar said that he can't, as the sunlight is too much for his eyes. Rabbi Yehoshua replied: "If even regarding the sun, which is one of the servants that stand before G - d, - you say that you are unable to gaze upon it. How then could you ever be able to behold the Divine Presence ?
The MAHARSHA as well as the MAHARAL commentate: If you are unable to gaze upon the sun, which is a physical entity, surely you cannot see G - d, who is metaphysical !
Source: Artscroll Talmud / Stone Edition