Milton, Paradise Lost, Book 7 invocation to Urania.
Half yet remaines unsung, but narrower bound
Within the visible Diurnal Spheare;
Standing on Earth, not rapt above the Pole,
More safe I Sing with mortal voice, unchang'd
To hoarce or mute, though fall'n on evil dayes, [ 25 ]
On evil dayes though fall'n, and evil tongues;
In darkness, and with dangers compast round,
And solitude; yet not alone, while thou
Visit'st my slumbers Nightly, or when Morn
Purples the East: still govern thou my Song, [ 30 ]
Urania, and fit audience find, though few.
https://milton.host.dartmouth.edu/reading_room/pl/book_7/text.shtml
