The brooding storm referred to in Act I Scene 2 and Act II Scene 2 act as a symbol of the brooding unrest in the Republic and also hint at the catastrophe to come. Sleep, and in particular dreams, are likewise used as a prediction of the disaster that will befall Caesar and through him, the Roman Republic. Insomnia seems to be a condition that affects many characters. Caesar ironically comments about men who can't sleep like Cassius and also finds his own sleep disturbed through the prophetic dream of Calphurnia. Brutus is unable to sleep the night before the battle of Philippi, with the ghost of Caesar appearing and telling him that they will meet again. This play therefore is a play full of omens, portents and signs that herald future tragedy and also hint at the profound impact of killing a leader such as Caesar.