چه كسي غزليات سعدي را به چهار دسته تقسيم نموده است؟ و به چه علت؟

Who Divided Saʹdiʹs Ghazals into Four Parts and Why?

Three questions have occupied my mind—and many others no doubt— for some time and this paper tries to answer these three questions. The first question is about the identity of the person who divided Saʹdiʹs ghazals into four parts of Tayyebat, Badayeʹ, Khavatim and Ghadim. The second question is about the reasons for this division and my last question concerns those weak and problematic ghazals which have not been excluded.