In Shakespeare's time, and for centuries afterwards, Brutus was regarded as a paragon of virtue, the perfect Roman aristocrat who put the welfare of the Republic before all other considerations.The Bruti were one of the leading patrician families in Rome, founders of the Republic five hundred years earlier, and Brutus is only too well aware of the legacy of family honor that falls upon his shoulders.

All the conspirators are well aware that they need Brutus to lend legitimacy to their scheme. His reputation for honor is such that, if he joins the conspiracy, everyone will accept that it must be in the public interest. Even Antony, his enemy, stresses the nobility of Brutus's character as he confirms this point of view:

This was the noblest Roman of them all:
All the conspirators save only he
Did that they did in envy of great Caesar;
He only, in a general honest thought
And common good to all, made one of them.
His life was gentle, and the elements
So mix'd in him that Nature might stand up
And say to all the world "This was a man!"

The word "gentle" here refers to Brutus's aristocratic mien and attitudes: he was a gentleman as well as a man. The Latin word for man is "vir," the root of the word "virtue," and Brutus often seems too virtuous to be human. He can also be appallingly priggish. He famously declares,

There is no terror, Cassius, in your threats,
For I am arm'd so strong in honesty
That they pass by me as the idle wind,
Which I respect not.

It is one thing to be honorable and honest, quite another to talk so loudly of one's own honor and honesty. Brutus is public-spirited and virtuous, but he is deeply sanctimonious in his awareness of his own virtue. He is known to this day for preferring his country to his friend, and this suits his personality perfectly: coldly public-spirited, harsh, and unforgiving—respected by many, loved by few.