In The Count of Monte Cristo, how is greatness defined?
Through the intrigue and suspense of the book, the idea of a truly great man runs afoul of greed, dishonesty, and treachery. The Count himself, despite his need for vengeance, is presented as a great man, a powerful force in the world that pushes back against societal convention, against evil, and against moral shortcomings.
We know the Count's vigorous and daring mind, denying anything to be impossible, with that energy which marks the great man ... the count had acquired an inconceivable relish for the contests in which he had engaged, sometimes against nature, that is to say, against God, and sometimes against the world, that is, against the devil.
(Dumas, The Count of Monte Cristo, gutenberg.org)
The Count is persistent and clever, but he is also deeply committed to his own code of ethics and morals; this shows when one of his plans results in the death of an innocent, and the Count mourns and questions his own judgements. A worse man would have ignored the event as collateral damage, but the Count worries that his own morals are degrading. This worry shows that under his ruthless drive for revenge, the Count is still a moral being, and able to make value judgements. Greatness could therefore be defined as courage of conviction, adherence to a strict moral code, and a resolve to keep one's word in the face of adversity.