Abu Sulayman Sijistani
Abu Sulayman Muhammad Sijistani, also called al-Mantiqi , named for his origins in Sijistan or Sistan province in present-day Iran, became the leading Persian philosopher of Islamic humanism in Baghdad.
Deeply religious, he regarded both religion and philosophy as valid and true; but separate, concerned with different issues, and proceeding by different means. He thus rejected the claims of the theologians employing Ilm al-Kalam to have built a theology "proved" by rationality and of the Brethren of Purity to offer a synthesis of philosophy and religion.
His best-known work is Siwān al-Ḥikma "Vessel of Wisdom", a history of philosophy from the beginning to his own time.
