Compassion derives from the Latin pair and the Greek Nathan, meaning "to suffer, undergo or experience." So "compassion" means "to endure [something] with another person," to put ourselves in somebody else's shoes, to feel her pain as though it were our own, and to enter generously into his point of view. That is why our hearts, discover what gives us pain, and then refuse, under any circumstance whatsoever, to inflict that pain on anybody else. Compassion can be defined, therefore, as an attitude of principled, consistent altruism.

Twelve Steps to a Compassionate Life