Ibrahim, as a collector of the reports about poets and singers, is an important source in his Aghānī.[140] Besides being a mine of information, Ishaq b. Ibrahim's terminology for the description of the melodic modes is preferred over that of his opponent, Ibrahim ibn al-Mahdi (162–224/778–839), and adopted by al-Isfahani in his Aghani.[141][lower-alpha 36] Furthermore, al-Isfahani embarked on the compilation of the Aghānī because he was commissioned by his patron to reconstruct the list of the exquisite songs selected by Ishaq.[143][lower-alpha 37] In other words, the raison d’etre of the Aghānī is partly related to al-Isfahani's idol, Ishaq b. Ibrahim, and its information about singers, songs and performance owes a tremendous amount to him.[144] Al-Isfahani's admiration for scholars or men of letters can be detected from time to time, usually in the passing comments in the chains of transmission.[145][146] Yet al-Isfahani outspokenly expresses his admiration, in some cases, such as that of Ibn al-Muʿtazz (247–296/862–909).[147][148][149]