What form, then, could contain the scope of these ideas?

The epic poem came into mind.

I thought about the great epics of the past.  Still read today, The Iliad and The Odyssey cover the Trojan War and its aftermath, creating vivid characters and situations deep with meaning.  Rome had Virgil’s Aeneid to build on the origins of a great empire.  Dante expressed a vision in The Divine Comedy that enfolded the Christian universe; Spenser wrote The Fairie Queene to explore the great virtues, and Milton looked at the fallen nature of man in Paradise Lost and Paradise Gained.

The epic has been acknowledged as one of the major poetic forms throughout history, both for the expression of its portrayals and the eloquence of its poetry.

I had made my decision.