At Isfahan, he completed his great work "Shifa", and also concluded his works on Ethics and al-Magest, while prior to that he had published the extracts of works on Geometry, Arithmetic and Music, and had worked out new problems in the books on Mathematics wherever he considered necessary. He added ten different figures to the al-Magest and worked out other problems hitherto unknown in Astronomy.
About his rare intellect, knowledge and wisdom, extraordinary details have come down to us. The fact that at the age of 18 he had mastered so many diverse subjects and sciences can only be attributed to his exceptional gift of intellect. Notwithstanding his remarkable intellectual capacity for understanding, he often went through the text repeatedly to have better knowledge, as he himself says in his book "Mantiq-I-Mashriqi" that at times he ponders over the new subject 200 times before he would give the final shape to it.