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In 2 Corinthians 12:1-3, Paul talks about one's experience with the 'third heaven'.
I must go on boasting. Although there is nothing to be gained. I will go on to visions and revaluations from the Lord. I know a man in Christ who fourteen years ago was caught up in the third heaven. Whether it was in the body or out of the body, I don't know - God knows. - 2 Corinthians 1-3 (niv)
What is the third heaven spoken about here?