It very often happens that the spirit already lifts the mind on high, yet that the flesh assails it with pressing temptations.
And, when the soul is led forward to the contemplation of heavenly things, it is struck back by the images of unlawful practice being presented.
For the sting of the flesh suddenly wounds him, whom holy contemplation was bearing away beyond the flesh.
Therefore heaven and hell are shut up together, when one and the same mind is at once enlightened by the uplifting of contemplation, and bedimmed by the pressure of temptation —
— so that both by straining forward it sees what it should desire, and through being bowed down it should be in thought subject to that which it should blush for.
For light springs from heaven, but hell is held of darkness.
Heaven and hell then are brought into one, when the soul which already sees the light of the land above, also sustains the darkness of secret temptation coming from the warfare of the flesh.
Yea, Paul had already gone up to the height of the third heaven, already learnt the secrets of Paradise, and yet being still subject to the assaults of the flesh, he groaned, saying:
But I see another law in my members warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members (Rom. 7:23).
How then was it with the heart of this illustrious Preacher, saving that God had ‘shut up together’ heaven and hell, in that he had both already obtained the light of the interior vision, and yet continued to suffer darkness from the flesh?
Above himself he had seen what to seek after with joy, in himself he perceived what to bewail with fear. The light of the heavenly land had already shed abroad its rays, yet the dimness of temptation embarrassed the soul.
Therefore he underwent hell together with heaven, in that assurance set him erect in his enlightenment, and lamentation laid him low in his temptation.
And it often happens that faith is now vigorous in the soul, and yet in some slight point it is wasted with uncertainty, so that both being well-assured, it lifts itself up from visible objects, and at the same time being unassured it disquiets itself in certain points.
For very often it lifts itself to seek after the things of eternity, and being driven by the incitements of thoughts that arise, it is set at strife with its very own self.
[…] Did not he experience that ‘earth and sea were shut up together’ in his breast, who, both hoping through faith and wavering through faithlessness, cried, Lord, I believe, help Thou mine unbelief? (Mark 9:23).
Gregory the Great (c.540-604): Reflections (Moralia) on Job, 10, 17-18 (on Job 11:10) @ Lectionary Central (slightly adapted).