This paper is concerned mainly with an unprecedented phenomenon, which deserves more examination and analysis: it is the Fatimid writers’ tendency toward finding a the interrelation between poetry and prose, and showing how far their memorization of poetry and prose effects the emergence of this phenomenon. Therefore, this paper attempts at unraveling three important aspects: first, identifying the concept, the beginnings of the interrelation; second, the genres of the interaction between a poem and a letter; third, the leitmotivs of the interrelation between a poem and a letter in the writings of Fatimid writers.