Here's why:
* Length and Scope: It's a long, complex poem that covers a vast and significant subject: the fall of mankind.
* Elevated Style: Milton uses formal language, elevated diction, and complex syntax.
* Supernatural Elements: Angels, demons, and the divine play key roles in the story.
* Heroic Characters: Although Satan is the protagonist, his actions and motivations explore themes of heroism, ambition, and rebellion.
* Focus on Fate and Destiny: The poem examines the consequences of free will and the nature of good and evil.
While some consider Paradise Lost to be a philosophical poem due to its deep exploration of theological and ethical questions, its core structure and characteristics place it firmly within the epic tradition.