The metaphysics of Ibn ʿArabī can be articulated in a single concept, the “Oneness of Being,” as expressed centuries earlier by Imam ʿAlī ibn Abī Ṭālib in his statement, “God is in everything but not by being contained within them, and separate from all things but not by being isolated from them.” The primary goal of the gnostic is to attain God through understanding reality and secondarily, to articulate spiritual experience in precise philosophical language. Dāʾūd al-Qayṣarī, a prominent Sufi metaphysician in the school of Ibn ʿArabī, presents the doctrines of mysticism in the introduction to his commentary on Ibn ʿArabī’s quintessential work, Fuṣūṣ al-ḥikam. This parallel English-Arabic edition includes a complete translation of the original Arabic text of Qayṣarī’s Prolegomena and aims to be a prerequisite text for the study of Fuṣūṣ al-ḥikam. The original text serves as a point of departure for elucidating major themes in Ibn ʿArabī’s thought as discussed by Qayṣarī as well as other exponents of his school, especially among the Shīʿī gnostics who have drawn extensively on Ibn ʿArabī’s metaphysics. Qayṣarī discusses key ontological and epistemological issues such as Being and its degrees, the divine names, the Universal Worlds, the Supreme Spirit, spiritual unveiling and the Perfect Human. The common thread underlying these seemingly disparate topics is the concept of the Oneness of Being. This is expressed in the following ideas: Being is the sole reality manifesting in the various degrees of existence. Each degree of Being is the self-disclosure of its essential perfections, which are the divine names, and the entities are the loci of manifestation of those names. In addition to the translation of the original text, the commentary deals with each chapter in detail addressing several important themes in mysticism. Because of the profound and universal nature of Qayṣarī’s text, the translation and commentary will serve as a contribution to any study of Islamic mysticism.