What is the main conflict in Memoirs of Hadrian by Marguerite Yourcenar?

Written in the form of a letter by Hadrian to his adopted grandson and eventual successor, Marcus Aurelius, Memoirs of Hadrian allows the protagonist to ruminate on the circumstances of his life and more importantly the inevitability of his death. The author of essentially a self-analytical autobiography, Hadrian is at once addressing his own mortality while orchestrating the exchange of authority and the transference of experience by composing a philosophical treatise on the nature of man, art, beauty, love, and statesmanship.