Nūn is the science of summary knowledge (ʿilm-i icmāl; the knowledge in which everything is contained in a summarized form). (Istilāḥ, 538)
In the verse "Nūn. By the pen..." (al-Qalam 68:1), the nūn refers to the summarized knowledge at the level of aḥadiyya (the station of divine oneness). The pen (qalam), on the other hand, is the station of detail (tafsīl), where the particulars of everything are specified. (Kāshānī, 98; Jāmiʿ, 102)
The intellect is nūn in the sense that sciences exist within it in a summarized (collective) manner; it is the pen (qalam) in the sense that knowledge is detailed (tafsīl) in the tablet (lawḥ). (Asfār, 245)
Nūn, in the most noble station, has no manifestation other than a single theophany. For it does not indicate multiplicity of manifestations, nor does it indicate multiplicity related to nobility or being most noble. The most noble has a station that is the most universal. Allah has commanded nūn to assist any of the summarized knowledges (ʿilm-i icmāl) under which there are details, with three hundred and sixty sciences. However, that which is detailed (tafsīl), not that which is specifically and exclusively summarized, has not been given to any other. Every summarized knowledge contains three hundred and sixty detailed sciences. These constitute the measure of Allah's knowledge among creation until the Day of Resurrection (yawm al-qiyāma). (Asfār, 246)