Tams (in the lexicon, meaning to erase, annihilate, or remove) is the disappearance of clarity from something that was clear. (Lumaʿ, 434)
Tams is the annihilation of something in such a way that no trace of it remains. (Hujwīrī, 466)
He saw the radiant light in the east
He immediately longed for the east
He would surely long for the west
If it had shone in the west
Here, it alludes to the vision (ruʾya) of the manifestation (tajallī) of the Real (al-Ḥaqq) in creation and in forms, and how this leads one to become attached to the cosmos because the manifestation appears in oneself. For the east is the place of cosmic manifestation (zuhūr). If, in reality, the manifestation of huwiya (the Divine Ipseity) called 'the west' had occurred in hearts, the lover would still yearn for the world of transcendence and the unseen, since he sees it in the eastern horizon, in the purest manifestation of forms, as the locus of manifestation. (Tercīmān, 54)
Berk (lightning) is the first radiant light that appears to the servant, calling him to the station (maqām) of nearness to the Lord so that he may journey in Allah (seyr fillāh). (Kāshānī, 36; Jāmiʿ, 78)
Hark is the middle of the manifestations (tajallī) that draw one into fanāʾ (annihilation in God). Its beginning is berk, and its end is tams fiʾl-Dhāt (annihilation in the Divine Essence). (Kāshānī, 59; Jāmiʿ, 81)
Tams is the complete disappearance of all forms in the attributes of the Light of Lights (Nūr al-Anwār). (Kāshānī, 65; Jāmiʿ, 89)
Berk is the first light that invites one to enter the path of Sufism (taṣawwuf). Its first subtlety is a light shining in the mirror of hope (rajāʾ). Through it, little grace appears as much, and much action seems little. The pains of destiny become sweetened by it. Its second subtlety is a light shining in the mirror of caution (ḥadhar) in the palace of aspiration on the horizon of unity. It leads to asceticism regarding created things and purifies the secret. Its third subtlety is a light shining in the mirror of need (iftiqār) from the side of grace. The river of pride flows, clouds of joy appear, and delight rains down. (Rawḍa, 490)
(See also: bawādiḥ-hujūm/hawājim; lawāʾiḥ-lawāmiʿ-tawāliʿ-tawāriq)