Brutus.  I will do so; but look you, Cassius—­
     The angry spot doth glow on Caesar’s brow,
     And all the rest look like a chidden train. 
     Calphurnia’s cheek is pale; and Cicero
     Looks with such ferret and such fiery eyes,
     As we have seen him in the Capitol,
     Being crost in conference by some senators.

   Cassius.  Casca will tell us what the matter is.

   Caesar.  Antonius—­

   Antony.  Caesar?

   Caesar.  Let me have men about me that are fat,
     Sleek-headed men, and such as sleep a-nights: 
     Yond Cassius has a lean and hungry look,
     He thinks too much; such men are dangerous.

   Antony.  Fear him not, Caesar, he’s not dangerous;
     He is a noble Roman, and well given.

   Caesar.  Would he were fatter; but I fear him not: 
     Yet if my name were liable to fear,
     I do not know the man I should avoid
     So soon as that spare Cassius.  He reads much;
     He is a great observer; and he looks
     Quite through the deeds of men.  He loves no plays,
     As thou dost, Antony; he hears no music;
     Seldom he smiles, and smiles in such a sort,
     As if he mock’d himself, and scorn’d his spirit,
     That could be mov’d to smile at any thing. 
     Such men as he be never at heart’s ease,
     Whilst they behold a greater than themselves;
     And therefore are they very dangerous. 
     I rather tell thee what is to be fear’d
     Than what I fear; for always I am Caesar. 
     Come on my right hand, for this ear is deaf,
     And tell me truly what thou think’st of him.

We know hardly any passage more expressive of the genius of Shakespeare than this.  It is as if he had been actually present, had known the different characters and what they thought of one another, and had taken down what he heard and saw, their looks, words, and gestures, just as they happened.

The character of Mark Antony is further speculated upon where the conspirators deliberate whether he shall fall with Caesar.  Brutus is against it: 

     And for Mark Antony, think not of him: 
     For “he can do no more than Caesar’s arm,
     When Caesar’s head is off.”

   Cassius.  Yet do I fear him: 
     For in th’ ingrafted love he bears to Caesar—­

   Brutus.  Alas, good Cassius, do not think of him: 
     If he love Caesar, all that he can do
     Is to himself, take thought, and die for Caesar: 
     And that were much, he should; for he is giv’n
     To sports, to wildness, and much company.

   Trebonius.  There is no fear in him; let him not die. 
     For he will live, and laugh at this hereafter.

They were in the wrong; and Cassius was right.

The honest manliness of Brutus is, however, sufficient to find out the unfitness of Cicero to be included in their enterprise, from his affected egotism and literary vanity.