Aimed at shedding some light on the intellectual process that historically led to the sophisticated elaborations and analyses of existence (wujud) and quiddity (mahiyyah) by such later Sufi metaphysicians as 'Abd al-Rahman al-Jami, 'Abd al-Ghani al-Nablusi, Mulla Sadra and others, the present work explores the position of a school of thought in the Islamic history—that is to say, later ash‘arisms as represented primarily by its two famous mutakallims, one from the 7th/8th century of Hijrah and the other from the 8th/9th century, namely: ‘Adud al-Din ‘Abd al-Rahman al-Iji (d. 756 H.) and al-Sayyid al-Sharif ‘Ali b. Muhammad al-Jurjani (d. 816 H.)—which was directly and actively involved in the intellectual debates about the nature of existence and quiddity that resulted in a creative synthesis of the aforementioned metaphysicians. It is therefore an attempt to survey how these two mutakallims, the former being the main actor and the latter being his commentator, dealt with the various positions adopted pertaining to the nature of existence and its relation to quiddity. In so doing, it selects al-Iji’s widely acclaimed kalam manual, al-Mawaqif, and the most famous among its many commentaries, the one done by al-Jurjani.