Compassion is best described by mystics.
When we hear talk on compassion from a true mystic, we instantly realize the truth in his understanding:
"This word “compassion” is composed of passion. To be compassionate means to be in love. Compassion is just a dimension of love. Passion is hasty, hectic, a little violent. Compassion is gentle, nice, understanding — but it is passion after all."
"Go deeper and deeper into meditation so you can go higher and higher in compassion. The deeper the roots of a tree reach the higher the peak. You can see the tree, you cannot see the roots, but they are always in proportion. If the tree is reaching to the sky the roots must be reaching to the very end of the earth. The proportion is the same. As deep as your meditation is, the same depth will be achieved in compassion. So compassion is the criterion. If you think you are meditative and there is no compassion, then you are deceiving yourself. Compassion must happen, because that is the flowering of the tree. Meditation is just a means towards compassion; compassion is the goal. Make yourself more and more alert. Call your name and answer, just to create more awareness. When you really become aware, you will feel a new upsurge of energy. Compassion will happen to you, and with compassion, bliss; with compassion, beatitude; with compassion, conviction."
"Passion arises out of negative nothingness and compassion arises out of positive nothingness."
"What is compassion? Compassion is the purest form of love. Sex is the lowest form of love, compassion the highest form of love. In sex the contact is basically physical; in compassion the contact is basically spiritual. In love, compassion and sex are both mixed, the physical and the spiritual are both mixed. Love is midway between sex and compassion. You can call compassion prayer also. You can call compassion meditation also. The highest form of energy is compassion."
(All quotes from a mystic named Osho, who was a naughty boy that created many problems for himself).