In the didactic genre one can mention Sanai's "Hadiqat-ul-Haqiqah" (Garden of Truth) as well as Nizami's "Makhzan-ul-Asrār" (Treasury of Secrets). Some of Attar's works also belong to this genre as do the major works of Rumi, although some tend to classify these in the lyrical type due to their mystical and emotional qualities. In addition, some tend to group Naser Khosrow's works in this style as well; however true gems of this genre are two books by Saadi, a heavyweight of Persian literature, the "Bustan" and the "Gulistan".