And the world of necessity indicates the permanent lights abstract from matter, while the world of possibility is the world of extinction—that which has no intellect in nomenclature, and whose survival or non-existence is permissible within the rational.

And the Necessary Existent (Wajib al-Wujud): is that whose existence is from its own essence and does not need anything at all.

And the possible (al-Mumkin) is what opposes the necessary, and it is that which is permissible to be and permissible not to be, like motions, colors, and sciences.

And verily absolute existence is necessary for the Creator specifically, and for other than Him it is possible, and the world of man is an isthmus (barzakh) between possibility and necessity.

And insight (al-Basirah) also according to the Sufis is the power of the heart, illuminated by the light of holiness, through which it sees the realities of things—their inwards and their outwards—and it is named according to the sages as the intellective faculty (al-'Aqilah), and it is in the position of sight for the soul, by which it sees the form of things through the theoretical intellective faculty.