And the heart is applied to the intellect, and it is like the concept, since it is the king of the senses and it is fountainhead of the spirit and the sanctuary of Allah which nothing other than Him can encompass. And the secret (al-Sirr) is a subtlety deposited in the heart like the spirit in the body, and it is the locus of witnessing, just as the spirit is the locus of love, and the heart is the locus of knowledge. And the lower soul (al-Nafs) expresses the sensory existence, while the intellect (al-'Aql) expresses the holy existence. And the heart, when it is engrossed in its beloved—the majesty of the beauty of the Essence—becomes occupied through it away from other attributes; and the attributes are loci of manifestation and appearances for the secret of the Essence. And insight (al-Basirah) is the intellect, intelligence, and the creed of the heart, and that by which a man's opinion and intellect are deduced concerning what is absent from him. And necessity (al-Wujub) is the necessity of the Essence's entailing its own self and its realization in the external reality. And possibility (al-Imkan) is the lack of the Essence's entailing either existence or non-existence.