Imam Khomeini has undertaken very useful discussions in his famous book "Combat with the Self" as following:
All of the corporeal worlds are dark veils. If the world is a means of directing attention to the Truth and for arriving at the abode of the Hereafter, which is the “abode of honor,” then the dark veils are transformed into veils of light.
“Being perfectly cut off from all else” means tearing and pushing aside all the dark and light veils, until one is able to enter the divine guest house which is the “source of greatness.”
Hence, in this intimate devotion (munajat) there is a request to God, the Exalted, for vision and brightness of the heart so one may tear the veils of light and reach the source of greatness: “Until the vision of the heart tears through the veils of light, so that there is union with the source of greatness.”
However, one who has not yet torn the veils of darkness, one who directs all of his attention to the natural world and, God forbid, becomes deviated from Allah, and one who is basically unaware of the world beyond and the spiritual worlds, and has retrogressed to a state of nature, who has never decided to refine himself, to set into motion his spiritual powers, to push aside the curtains of darkness which are a cloud over his heart, Imam further explains.
He is lodged in ‘the deepest of the depths’ [of hell] which is the ultimate veil.
“Then we render him the lowest of the low” (Q 95:5),
While the God of the worlds has created man in the most lofty state and station.
“Indeed we have created man in the best of molds” (Q 95:4).
If one follows the desires of the self and from the day he becomes acquainted with himself pays no attention to anything other than the dark wilderness and never thinks that it is possible that aside from this polluted dark world that there exists another place and station, then he will have sunk into the veil of darkness and have become an instance of,
“But he clung to the earth and followed his low desire” (Q 7:176).
Read more:
Imam Khomeini warned of performing deeds for sake of others