The juxtaposition of Cicero’s grave warning about not walking in this night’s disturbing weather with Cassius’s self-satisfied mood upon meeting with Casca (he labels the night “very pleasing . . . to honest men” [I.iii.43]) aligns Cassius with the evil that the omens portend. Further, this nexus suggests a sort of pathetic fallacy—an artistic device by means of which an inanimate entity assumes human emotions and responses (Shakespeare was especially fond of employing pathetic fallacy with nature in moments of turmoil, as in Macbeth, when the night grows increasingly eerie until Macbeth observes that “Nature seems dead” right before he goes to murder King Duncan [II.i.50]). In Julius Caesar, the terrifying atmosphere of supernatural phenomena reflects Cassius’s horrific plan to murder Caesar.
Furthermore, Cassius not only walks about freely in the atmosphere of terror but relishes it: “And when the cross blue lightning seemed to open / The breast of heaven, I did present myself / Even in the aim and very flash of it” (I.iii.50–52). He insinuates that the “monstrous state” of which the heavens warn refers to Caesar and his overweening ambition, yet he himself has become something of a monster—obsessed with bringing Caesar down, brazenly unafraid of lethal lightning bolts, and haughty about this fearlessness (I.iii.71). As Casca notes, “It is the part of men to fear and tremble” at such ill omens; Cassius seems to have lost his humanity and become a beast (I.iii.54).
The various omens and portents in Julius Caesar also raise questions about the force of fate versus free will. The function and meaning of omens in general is puzzling and seemingly contradictory: as announcements of an event or events to come, omens appear to prove the existence of some overarching plan for the future, a prewritten destiny controlled by the gods. On the other hand, as warnings of impending events, omens suggests that human beings have the power to alter that destiny if provided with the correct information in advance.