So by the ships the other lords of Achaea’s armies
slept all night long, overcome by gentle sleep…
But not the great field marshal Agamemnon –
the sweet embrace of sleep could not hold him:
his mind kept churning, seething. Like Zeus’s bolts
when the lord of bright-hatred Hera flashes lightning,
threatening to loose torrential rain or pelting hail
or snow when a blizzard drifts on fields – or driving on,
somewhere on earth, the giant jaws of rending war –
so thick-and-fast the groans came from Atrides,
wrenching his chest, heaving up from his heart
and rocked his very spirit to the core.

– Homer

The Iliad, Book 10, lines 1-12. While the other Greek commanders sleep soundly that night, Agamemnon does not. He feels grim about the military situation and is concerned about the fate of the Achaean army after their rout by the Trojans earlier that day. An epic simile compares the turmoil in his heart to Zeus flashing lightning and threatens to let loose a massive storm.