Compassion (karuṇā) is the second virtue which when cultivated makes one sublime, soft, rid of hard-heartedness and cruelty. It is defined as that which affects a man to see others in trouble and suffering. (Paradukkhe sati sādhūnaṃ mana kampetīti karuṇā ti. Majjhima Nikāya Ṭīkā 1.1). When man is endowed with this feeling, he does not want to inflict pain on others. His heart melts when seeing others suffer. He wants to remove all their suffering and makes all efforts to do so. He wants to help others even at his own cost, without caring for his comfort and convenience, without caring for even his own life. Karuṇā is synonymous with avihiṃsā (non-injury, mercy, friendliness, love). A person endowed with this exalted feeling combats and destroys the sufferings of others (Kināti vināseti vā paradukkhanti karuṇā. Abhidhammāvatāra ṇāmarūpaparicchedādi, p.22). The characteristic of karuṇa (compassion) is to remove the sufferings of others; its function is not to tolerate others’ sufferings. It is manifested in avihiṃsā and its immediate cause is the helplessness of the sufferers (Sā paradukkhāpanayanākārappavatti lakkhaṇā, paradukkhāsahanarasā, avihiṃsāpaccupaṭṭhāna, dukkhābhibhūtānaṃ anāthabhāvadassana padaṭṭhānā. ibid, p.22).
Compassion is opposed to cruelty, to hard-heartedness. There are many in this world, who badly need compassion. The physically ill and the mentally sick, the poor and the downtrodden who live their lives in abject poverty, the illiterate who do not understand what their rights are and how they can ameliorate their conditions, the servants who are ill-treated and justice is not meted out to them, the women who are treated as second rate citizens of the world, the old who are not looked after by their children, the beggars who are compelled to go begging – all need compassion. Unless one has compassion for them, how can one open charitable hospitals to treat the sick, to start schools to educate the poor children, to start orphanages to take care of the children who do not have anybody to look after. Compassion makes us do altruistic works. It is because of this sublime virtue that many compassionate persons are engaged in doing many social activities for the poor and the needy. This is called Socially Engaged Buddhism in the present time.
Inspired by this sublime virtue, the rich can make the best use of their wealth and the experts in their fields can do works to ameliorate the poor conditions of a large section of humanity. The Buddha with his great compassion always looked for the poor, the ignorant and the depraved and helped them better their lives. The Buddha himself served the sick. He exhorted his disciples to attend upon the sick (Yo, bhikkhave maṃ upaṭṭhaheyya, so gilānaṃ upaṭṭhaheyya. Mahāvagga, p.394)
He who is desirous of practicing karuṇā must first see what dangers there are if he has no compassion and what advantages there are if he develops and practices it. While practicing it, he should not practice it on his dear ones; because they will remain the same for him, he cannot have karuṇā for them. Nor should he practice it on a neutral or a hostile person, nor on the opposite sex, nor on somebody who is dead because he cannot really develop karuṇā for them. They are not the right fields for practicing karuṇā.
He should practice it first by seeing a really unfortunate person like one who is helpless with his hands and feet cut off or who is helpless by all means. If such a person is not available then he can practice compassion on a person who is an evil–doer since this person may look happy as long as he is not caught but once he is caught, he will be taken to a place of execution by the order of the authorities and given punishment.
Gradually, one should start practicing compassion on one’s own relatives.