Dante Alighieri, in Canto II of The Inferno:
O Muses, O high genius, aid me now!
O memory that engraved the things I saw,
Here shall your worth be manifest to all!
(Anthony Esolen translation, 2002)
John Milton, opening of Book 1 of Paradise Lost:
Of Man’s first disobedience, and the fruit
Of that forbidden tree whose mortal taste
Brought death into the World, and all our woe,
With loss of Eden, till one greater Man
Restore us, and regain the blissful Seat,
Sing, Heavenly Muse, […]
William Shakespeare, Act 1, Prologue of Henry V:
Chorus: O for a Muse of fire, that would ascend
The brightest heaven of invention,
A kingdom for a stage, princes to act
And monarchs to behold the swelling scene!