None of us, no human has seen or comprehended the depth of darkness in our hearts.
As Calvin taught we are totally depraved, not that we nessisarily are that bad but we have the potential.
I think that anyone who did glimpse the true nature of there soul they would either go mad or in horror seek Jesus.
It is only Jesus who can undo this state.
It seems that Isaiah did...
6 In the year of King Uzziah’s death I saw the Lord sitting on a throne, lofty and exalted, with the train of His robe filling the temple. 2 Seraphim were standing above Him, each having six wings: with two
each covered his face, and with two
each covered his feet, and with two
each flew. 3 And one called out to another and said,
“Holy, Holy, Holy, is the Lord of armies.
The whole earth is full of His glory.”
4 And the foundations of the thresholds trembled at the voice of him who called out, while the temple was filling with smoke. 5 Then I said,
“Woe to me, for I am ruined!
Because I am a man of unclean lips,
And I live among a people of unclean lips;
For my eyes have seen the King, the Lord of armies.”
6 Then one of the seraphim flew to me with a burning coal in his hand, which he had taken from the altar with tongs. 7 He touched my mouth
with it and said, “Behold, this has touched your lips; and your guilt is taken away and atonement is made for your sin.”