Taken from the words of the Hidden Pole and the Known Muhammadan Seal, Shaykh Ahmad al-Tijani (may Allah sanctify his noble secret)

Know that what veils creation from Allah Most High is their resting [inclining] in other than Him. Were it not so, they would all behold Him with the eye of inward sight [basa’ir], plainly and directly. Yet some are more deeply veiled than others, though all alike are veiled from Him—since distance, place, direction, and spatial relation are impossible with respect to Him, exalted and glorious. The matter is only according to the measure in which the servant is veiled from witnessing Him.

A group is veiled by love of this lower world and by plunging into it; and this is the greatest of veils.

Another group is veiled from Allah Most High by their lusts, their ulterior motives, their whims, and their own selves; and this is lesser than the first.

Another group is veiled by the Hereafter—by its varieties of bliss, its maidens and palaces, and by the painfulness of its punishment and the fear of the depths of Hell.

Another group is veiled from Allah Most High by their settling upon sciences, branches of knowledge [ma’arif], secrets, lights, states, and stations—because these have become their aim from Allah Most High and what they seek of Him. They find repose when such things are present, and are thrown into agitation when they are absent.

But the true knowers have torn through all these veils, and they sit in the Divine Presence upon the carpet of direct witnessing, having cast off the beholding of states and stations and the desire for them, for they are among the created things from which the true knowers have departed.

The first are more greatly veiled than those who come after them, because they are veiled by the first veil in addition to the second.

The people of the second veil have torn through the first veil by renunciation; yet the impulses of the self and desire cut off the path before them, and so they were veiled.

The people of the third veil have torn through the first two veils; yet the delight of everlasting bliss cut off the path before them, and so they were veiled.

The people of the fourth veil have torn through the three veils; yet the desire for elevation and rank through the attainment of stations cut off the path before them.

The first three, however, are veiled by layers of darkness; while the latter are veiled from Allah Most High by lights. All are equal in this: that they did not look toward Allah Most High.

And whoever tears through all the veils looks upon Allah Most High with the eye of inner sight.