Co-related with these books on "good qualities" stand, in our opinion, the books on "good morals and their opposite," or "goodness and wickedness," Kutub al Mahasin wal Azdad, or Kutub al Mahasin wal Masawi. Although in the Fihrist we do not come across books with this title, we have a book so named from the beginning of the tenth century whose author was Ibrahim ibn Muhammad al Baihaki.
We give below from the two works al Mahasin wal Masavi and al Mahasin wal Azdad extracts bearing on Persian subjects. The list of Persian subjects comprised in these Arabic books afford us a sufficient idea of the wealth and variety of the material on these points to be recovered from Arabic discourses on manners and morals.
Under the title of Kitab al Mahasin wal Azdad we likewise possess a work ascribed to Jahiz. Both these books evidently go to a common origin. It is quite possible that antithesis was originally not excluded from these Kutub al-Mahasin, from which were developed a special species of educative treatises, those on "good qualities and their opposites."