From 1927 to 1932, Asín published a 5-volume study, "Abenházam de Córdoba y su historia crítica de las ideas religiosas" Hazm of Cordoba and his "Critical History of Religious Ideas". Asín's first volume presents a biography, including his life as a jurist/politician and his trail through the world of intellect; Asín here gives a critique of the writings of the medieval Spanish Muslim, focusing on Ibn Hazm as a theologian and as an early historian of religions. The remaining four volumes comprise an incomplete yet lengthy translation of Ibn Hazm's "Fisal", a very long work on the history of religious ideas, its Arabic title being "Kitab al-Fisal fi al-milal wa-al-ahwa' wa-al-nihal" of Separation. Concerning Religions, Heresies, and Sects.