How we cite our quotes:
Well, Brutus, thou art noble; yet, I see
Thy honorable mettle may be wrought
From that it is disposed; therefore it is meet
That noble minds keep ever with their likes;
For who so firm that cannot be seduced? (1.2.24)
Even though Cassius thinks Brutus is a "noble" guy, he also thinks that just about anyone, including Brutus, can be manipulated or "seduced."
I will this night,
In several hands, in at his windows throw,
As if they came from several citizens,
Writings, all tending to the great opinion
That Rome holds of his name, wherein obscurely
Caesar's ambition shall be glanced at.
And after this let Caesar seat him sure;
For we will shake him, or worse days endure. (1.2.24)
Cassius hopes that by planting fake letters from "citizens" urging Brutus to lead Rome, Brutus will be convinced to join the conspiracy against Julius Caesar.
I can as well be hang'd as tell the manner of it. It was
mere foolery; I did not mark it. I saw Mark Antony offer him a
crown (yet 'twas not a crown neither, 'twas one of these
coronets) and, as I told you, he put it by once. But for all
that, to my thinking, he would fain have had it. Then he offered
it to him again; then he put it by again. But, to my thinking, he
was very loath to lay his fingers off it. And then he offered it
the third time; he put it the third time by; and still as he
refused it, the rabblement hooted and clapped their chopped hands and threw up their sweaty nightcaps and uttered such a deal of stinking breath because Caesar refused the crown that it had
almost choked Caesar, for he swounded and fell down at it. And
for mine own part, I durst not laugh for fear of opening my lips
and receiving the bad air. (1.2.29)
Caesar deliberately deceives the public here. It's clear he's putting on a great show by refusing the crown, even though he'd secretly love to have it. He understands that public refusal is a smart political maneuver to get the people to love him more and think him less ambitious.