How does Marcus Brutus demonstrate courage? I need as many quotes from the book and examples to support the answers as well.

In Shakespeare's Julius Caesar, Brutus demonstrates his courage and fortitude in his acting upon his convictions.  And, while Marc Antony ironically desparages Brutus in his funeral oration for Caesar by saying, "And Brutus is a noble man, so are they all noble men," he admits at the end of the play in his funeral oration for Brutus:

This was the noblest Roman of them all

All the conspirators, except him,

Did that they did out of jealousy of great Caesar;

Only he, in a general honest thought

And common good to all, made one of them.

His life was gentle, and the elements

So mixed in him that Nature might stand up

And say to all the world, "This was a man." (5.5.74-81)

In his soliloquy, Brutus debates with himself after speaking with Cassius and decides that he must act for the good of Rome.  In his convictions he has the courage to decide to join the conspirators:

And for that reason we must think of him as a serpent's egg

Which hatched would as his kind grow dangerous,

And kill him in the shell. (2.1.32-34)

In this same act, Ligarius compliments Brutus, "Brave Son, fathered from honorable loins..." (2.2.335)

When his wife Portia comes to Brutus and begs him to reveal what troubles him, Brutus spares her the anxiety by not telling her of his plans.

When Cassius expresses doubt of their success in battle, Brutus replies courageously,

There is a tide in the affairs of men

Which taken at the flood, leads on to fortune,

Omitted, all the voyage of their life

Is bound in shallows and in misery. (4.3.218-222)

As he and Cassius argue, Brutus shows fortitude in accepting what has happened to their friendship:

The deep of night is crept upon our talk

And nature must obey necessity. (4.3..251-252)

Before they go into battle, in spite of his grief over Portia's death and his premonition that they will be defeated, Brutus, still bravely committed to his love for Rome, bids good bye to his brother-in-law:

Forever and forever farewell, Saccius

If we do meet again, why we shall smile;

If not,why then this parting was well made. (5.1.125-128)

 Clearly, from beginning to end, Brutus displays fortitude as he courageously remains true to his ideals.