When lights (nūr) are spread over it, the eye perceives all that can be seen; the perception of the eye depends on its own light, as well as the light of the sun, a lamp, or similar sources.
The eye of inner insight (baṣīra) is the same. In this way, the veil over the eye of baṣīra consists of desires (ḥirṣ), lusts (shahwa), thinking of things other than Allah (taking into account, considering), and similar things. Because of these, a barrier comes between it and the malakūt (the spiritual realm of the unseen). When a person turns to the mirror of the qalb (the heart) and polishes it with various forms of ascetic discipline (riyāḍāt) and spiritual struggle (mujāhadāt), all veils are removed from it. The light (nūr) from it unites with the light that opens to the realm of the unseen. Thus, the people of the malakūt gradually begin to appear. This is like the sun in the world of the senses. Along with this, the light of the eye of baṣīra combines with the light of discernment (tamyīz), and then the knowledge of the unseen is unveiled as it truly is. (Tadbīrāt, 170)