 Besides the overall treatment of metaphysics in the summae, Avicenna investigates particular metaphysical areas in specific treatises, such as the Book of Provenance and Destination (Kitāb al-Mabdaʾ wa-l-maʿād), which focuses, within metaphysics, on philosophical theology, or the Epistle of Immolation about Destination (Al-Risāla al-aḍḥawiyya fī amr al-maʿād), which concentrates on a specific topic of philosophical theology, or in allegorical writings, such as the Ḥayy Ibn Yaqẓān or the Epistle of the Bird (Risālat al-Ṭayr). Various issues pertaining to metaphysics are extensively debated in works that contain his reflections on key philosophical themes, such as the Notes (Taʿlīqāt), or that derive from the teaching activity and the dialectical practices performed within his circle, i.e., the Discussions (Mubāḥaṯāt). Related to metaphysics are the specific essays ascribed to Avicenna and devoted to the philosophical and allegorical interpretation of some Qur’anic verses, whose authenticity however remains to be assessed.