As Cicero leaves, Cassius enters, and again Shakespeare signals the (open-air/daylight) audience that this is a night-time scene by Cassius’ “Who’s there?” (it’s difficult to see at night), and “Casca, by your voice” (easier to identify by sound at night-time). We are also reminded of the disturbances elaborated upon in the opening sub-scene (1-40), and indeed thunder punctuates the conspiratorial conversation between Cassius and Casca (conspiracy seems to be emphasized simply because there are only two of them?). Noteworthy is Casca’s initial response to Cassius–“A Roman,” which encapsulates much in a single word, much as it would if an American, for example, did the same–though the values and concepts might well be different from what Casca means by “A Roman.” In fact, Cassius’s manipulation of Casca (who incidentally seems to a rather different person from that presented on his first appearance in 1.2) serves to bring out some of the characteristics of what it means to be a Roman, especially when that is threatened by “the senators to-morrow / mean to establish Caesar as a king.” Cassius has led up to this point with his lengthy speech (57 ff) that challenges Casca’s cowardly behaviour. One feature of that speech is the use of the rhetorical figure of anaphora (the series of somewhat parallel phrases beginning with “why”). Shakespeare uses the device frequently in his plays and usually as a means of alerting the audience that something special is being said (as indeed is usually the purpose of any striking rhetorical device). Cassius’ dominance of the conversation serves a similar function, at least so far as character is concerned–Casca has few lines, though his response “So every bondman in his own hand bears / The power to cancel his captivity” (101-02) demonstrates the efficacy of Cassius’ oratory, as does their handshake when Casca agrees to join Cassius plot.
There is not space here to delve deeper into the imagery/words of this sub-scene, though suffice to say it is worth close examination–for example, the use of animal imagery in Cassius’ speech 103 ff. Although the use of “wolf” and “sheep” is commonplace, it should be placed in the context of what is sometimes called the Great Chain of Being, in which man’s position in the hierarchy of things is above that of animals by virtue of his exercising rational powers. To say a Roman is behaving as a sheep implies both cowardice and irrationality, broadly construed.
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