Percy Bysshe Shelley

To the Nile

Month after month the gathered rains descend
Drenching yon secret Aethiopian dells,
And from the desert's ice-girt pinnacles
Where Frost and Heat in strange embraces blend
On Atlas, fields of moist snow half depend. 
Girt there with blasts and meteors Tempest dwells
By Nile's aereal urn, with rapid spells
Urging those waters to their mighty end.
O'er Egypt's land of Memory floods are level
And they are thine, O Nile—and well thou knowest 
That soul-sustaining airs and blasts of evil
And fruits and poisons spring where'er thou flowest.
Beware, O Man—for knowledge must to thee,
Like the great flood to Egypt, ever be.