The Talmud states that Moses would prophesy by peering through a transparent lens, while the other prophets would observe their prophecies through a non-transparent lens (a mirror) .
It would thus be expected that Moses would experience God more clearly than would the other prophets.
But as our Sages noted, the verses imply the opposite.
Isaiah, who prophesied through a non-transparent lens, said, “I saw the Lord” (Isa. 6:1); Ezekiel said, “I saw, and behold, there was a likeness” (Ezek. 8:2).
Yet Moses, who observed his prophecy through a transparent lens, records God as saying, “A man shall not see Me and live” (Ex. 33:20).
When understood correctly, these verses pose no contradiction.
A transparent lens is completely clear, and so a person looking through it, unhindered by anything whatsoever, is able to see the truth, which is that he does not see.
By contrast, a person looking through an obscure lens, to whatever degree, will perceive some kind of image in it.
Therefore, the prophets looking through a non-transparent lens saw something, and the less clear the lens, the more they saw.
Rabbi Adin Steinsaltz