In Buddhism there are many concepts of a Bodhisattva. To me a Bodhisattva is a person who has reached enlightenment and chooses to remain among the living to help the rest of us also achieve enlightenment. There is some parallel to Christian saints.
Let me be the first to suggest that John McCain will be the first presidential candidate who is clearly a Bodhisattva. We have Bodhisattvas all around us.
I often point out that fireman and ambulance workers risk their lives every day to save the life of strangers. They are Bodhisattva as are the people who work in emergency rooms and on contagious wards.
The evidence that John McCain is a Bodhisattva can be seen in his primary role as a mediator, the leading mediator, in the U.S. Senate, the incredible and bottomless honesty that is known to everyone around him, and his willingness to get angry (but never stay angry) despite the American publics' dislike of people who show anger.
McCain probably became a Bodhisattva during the six years of torture he suffered in North Vietnam. When one has endured suffering and torture, one either becomes insane, bitter or enlightened. Jesus acted as a Bodhisattva when he said, 'forgive them, they don't know what they have done' when he purportedly had nails in his hands and feet. McCain became the Bodhisattva.
The origin of the word penitentiary comes from the religious believe that prison could make a sinful criminal become a penitent, deeply religious humble person.