Here is a brief but interesting summary of the impact and influence of Neo-Platonisn on Islamic thought by Ian Richard Netton who is the author of a number pf works on Islamic philosophy and mysticism. He writes:
Islamic Neoplatonism developed in a milieu already saturated with the thought of Plotinus and Aristotle. The former studied in Alexandria, and the Alexandrine philosophical syllabus included such figures as Porphyry of Tyre and Proclus. Associated with these scholars were two major channels of Islamic Neoplatonism, the so-called Theology of Aristotle and the Liber de Causis (Book of Causes). Other cities beloved of the philosophers at the time of the rise of Islam in the first century ah (seventh century ad) included Gondeshapur and Harran.
Islamic Neoplatonism stressed one aspect of the Qur’anic God, the transcendent, and ignored another, the creative. For the Neoplatonists, all things emanated from the deity. Islamic philosophers were imbued to a greater or lesser degree with either Aristotelianism or Neoplatonism or, as was often the case, with both. Al-Kindi, the father of Islamic philosophy, has a Neoplatonic aspect, but the doctrine reaches its intellectual fruition in the complex emanationist hierarchies developed by al-Farabi and Ibn Sina. Their views are later developed (or metamorphosed) by later thinkers into an emanative hierarchy of lights, as with Shihab al-Din al-Suhrawardi, or the doctrine of the Unity of Being espoused by Ibn al-‘Arabi. While al-Ghazali and Ibn Rushd both vigorously opposed Neoplatonic views, the latter attacked the former for his general opposition to the philosophers.
Neoplatonism itself had a major impact on that sectarian grouping of Muslims known as the Isma’ilis, and became the substratum for its theology. Historically, Neoplatonism in Islam achieved its climax with the Fatimid Isma’ili conquest of Egypt towards the end of the fourth century ah (tenth century ad). While Neoplatonism later declined in philosophical importance in the face of rampant Aristotelianism and Hanbalism, it may be said to have bequeathed an important religious, historical and cultural legacy to the Islamic world, which in the Isma’ili movement endures to this day.
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