In Act 2 of Shakespeare's Julius Caesar, we're introduced to some truly fantastical happenings that, according to Calphurnia, spell doom for Caesar. In Act 2, Scene 2, Calphurnia describes these dire portents at length in an attempt to prevent Caesar from visiting the Senate and risking life and limb (the following quote is taken from eNotes' excellent online version of the text):
There is one within,
Besides the things that we have heard and seen,
Recounts most horrid sights seen by the watch.
A lioness hath whelped in the streets;
And graves have yawn'd, and yielded up their dead;
Fierce fiery warriors fight upon the clouds,
In ranks and squadrons and right form of war,(20)
Which drizzled blood upon the Capitol;
The noise of battle hurtled in the air,
Horses did neigh and dying men did groan,
And ghosts did shriek and squeal about the streets.
O Caesar! These things are beyond all use,
And I do fear them. (16-26)
In short, Calphurnia has heard of supernatural occurrences that seem consistent with an impending apocalyptic event. Since Calphurnia has also just had a bad dream in which Caesar is essentially murdered (she dreams of Caesar's statue oozing blood), she interprets these events as signs of Caesar's impending doom and tries to convince him to stay home and miss his visit to the Senate. Unfortunately, Caesar goes to the Senate anyway and meets his doom, just as Calphurnia feared.