This volume is based on the 35th Cologne Medieval Studies Conference on the Duration of Being.

The present study relies on a greatly improved re-edited text of Ibn B a s (d. 1139) commentary on De anima, Kit?b al-nafs.Here, the author showsthat in keeping with the Aristotelian model, Ibn B a conceptualizes psychology as a natural science, but at the same time, ultimately turns his understanding of natural science into fundamental science."