Grant me the Muse, ye gods! whose humble flight
Seeks not the mountain-top's pernicious height:
Who can the tall Parnassian cliff forsake,
To visit oft the still Lethean lake;
Now her slow pinions brush the silent shore,
Now gently skim the unwrinkled waters o'er,
There dips her downy plumes, thence upward flies,
And sheds soft slumbers on her votary's eyes.

William Cowper

http://www.poemhunter.com/poem/in-a-letter-to-c-p-esq-ill-with-the-rheumatism/