At one point in Act I, Brutus tells Cassius,
...for the eye sees not itself
But by reflection, by some other things. (1.2.54-55)
Cassius then responds,
And since you know you cannot see yourself
So well as by reflection, I, your glass. (1.2.69-70)
This is followed in Act IV by Brutus telling Cassius, "I do not like your faults," (4.3.92) and Cassius responds with "A friendly eye could never see such faults." (4.3.93)
What literary device is best exemplified in Cassius' last comment, and what change in meaning takes place from act to act?