Compassion has as its near enemy "grief, based on the homelife". This is dosa, conditioned by attachment which is connected with "worldly life", that is, attachment to people and pleasant things. Compassion has as its far enemy cruelty (Vis. IX, 99). one cannot practise compassion while one is cruel.  

     As regards the near enemy, grief or aversion, we may take for compassion what is actually aversion, dosa. When we see someone else who is in miserable circumstances, there tend to be different types of cittas, not only kusala cittas with compassion but also akusala cittas. There are moments of compassion when we wish to help someone in order to allay his suffering and there can also be moments of aversion about his suffering. Compassion and aversion can arise closely one after the other and it is difficult to know their different characteristics. Through right understanding one can come to know their difference.

     Compassion is different from loving kindness. Loving kindness is the cetasika which is non-aversion, adosa. This cetasika arises with every sobhana citta, but when it has the special quality of loving kindness, metta, it is directed towards beings; it "sees the lovableness of beings", according to the Visuddhimagga and and promotes their welfare. when there is loving kindness one treats others as friends. Compassion wants to allay beings' suffering. Thus, the objectives of loving kindness and compassion are different. For example, in the case of visiting a sick person, there can be moments of loving-kindness when we give him flowers or wish him well, but there can also be moments of compassion when we notice his suffering.

     We may think that since compassion is directed towards beings who are suffering, there cannot be pleasant feeling accompanying it. However, compassion can arise with pleasant feeling or with indifferent feeling. One can with joy alleviate someone's suffering.

     At the moment of compassion there is calm. Compassion can be developed as a mediation subject of samatha by those who have accumulations to do so. The Visuddhimagga (Chapter IX, 77-124) describes how compassion as one of the divine abidings is to be developed as meditation subject leading to the attainment of jhana (1 With compassion as meditation subject different stages of rupa-jhana can be attained, hut not the highest stage, since the jhanacittas of the highest stage of rupa-jhana are accompanied by indifferent feeling. Compassion can be accompanied by pleasant feeling or by indifferent feeling and thus it is not the object of the jhanacittas of the highest stage.). Compassion is developed for the purpose of purification from cruelty. When jhana is attained compassion can be extended to all beings, and then it has become unlimited.

     The Buddha who taught Dhamma out of compassion exhorted the monks to be kind and compassionate to others. Compassion can and should be developed in daily life. The Buddha himself visited the sick and asked the monks to do likewise. They should attend to both the physical and the mental needs of the sick. We read in the Gradual Sayings (III, Book of the Fives, Chapter XIII, 4) how one attends to the sick in the wrong way and how in the right way:

Monks. possessing five qualities one who waits on the sick is not fit to help the sick. What five?
     He cannot prepare medicaments; does not know physic from what is not physic, offers what is not. does not offer what is; in hope of gain waits on the sick not from good-will; loathes to move excrement, urine, puke and spittle: nor can he from time to time instruct, rouse, gladden and satisfy the sick with Dhamma-talk.
     Monks, possessing these five qualities one who waits on the sick is not fit to help the sick (Possessing the apposite qualities he is fit to help. )
These words of the Buddha were motivated by his great compassion. Whenever he visited the sick he would explain Dhamma to them (1 For example in Kindred Sayings V, Maha-vagga, Book XI, Kindred sayings on Streamwinning, 3, Dighavu.).
     We read in the Gradual Sayings (III, Book of the Fives, Chapter XXIV, 5, Taking Pity) that the Buddha explained to the monks about different deeds of compassion towards householders :
Monks, if a monk in residence follow the course of five things, he takes pity on householders. What five?
     He incites them to greater virtue; he makes them live in the mirror of Dhamma: when visiting the sick he stirs up mindfulness, saying: "Let the venerable ones set up mindfulness, that thing most worth while!"; when many monks of the Order have come, he urges the householders to do good... ; and when they give him food, whether mean or choice, he enjoys it by himself nor frustrates (the effect of that ) gift of faith.
     Verily, monks. ... he takes pity on householders. 
When householders give the monk a gift, no matter whether it is "mean or choice", the monk should accept it out of compassion, in order to help the householders to accumulate wholesomeness. 

     There are many ways of extending compassion to others. When we understand that we should not hurt or harm others we may out of compassion refrain from wrong speech and wrong action. We read in the Middle Length Sayings (I, no. 27, Lesser Discourse on the Simile of the Elephant's Footprint) that the Buddha, while he was staying at Savatthi, spoke about the monk who trains himself in order to attain arahatship. The Buddha said about the observing of sila: 
He, being thus one who has gone forth and who is endowed with the training and the way of living of monks, abandoning onslaught on creatures, is one who abstains from onslaught on creatures: the flick laid aside, the knife laid aside, he lives kindly, scrupulous, friendly and compassionate towards all breathing things and creatures...
The Buddha then spoke about the abstinence of the other kinds of akusala kamma. If we see the benefit of compassion it is a condition for developing it in daily life whenever there is an opportunity for it. Sometimes there is an opportunity to alleviate physical suffering and sometimes mental suffering. Someone may treat us in an unjust way by speech or by actions, but, when we consider that he will receive the results of his own deeds, compassion can arise instead of anger. Understanding of kamma and vipaka can condition compassion.

     It is the Buddha's greatest deed of compassion to teach Dhamma since in this way beings' greatest suffering, their being in the cycle of birth and death, can be overcome. It is due to the Buddha's great compassion that we today can develop the way leading to the end of suffering. There are many degrees of compassion. It can arise without right understanding or with right understanding. To the extent that right understanding develops, all good qualifies and thus also compassion develop. Compassion can accompany the eight types of maha-kusala cittas, but it does not arise at all times with these areas, since there is not always opportunity for compassion. Compassion does not accompany the maha-vipakacittas, cittas which are results of kusala kamma of the sense-sphere, because compassion has living beings as object. Compassion can accompany the maha-kiriyacittas of the arahat.

     As regards rupavacara cittas, compassion can accompany the rupavacara cittas of the first, second and third stage of jhana of the fourfold system (and the fourth stage of the fivefold system) but not those of the highest stage of jhana (1 Thus, compassion can accompany twelve types of rupavacara cittas (Vis. XIV, 157, 181). See Appendix 8.).

    Compassion does not accompany arupavacara cittas nor does it accompany lokuttara cittas, since the object of lokuttara cittas is nibbana.

     Sympathetic joy, mudita, is the appreciation of someone else's good fortune. We may think that sympathetic joy is pleasant feeling, but mudita is not feeling. In order to understand its nature we should study what the Visuddhimagga IX, 95) states about mudita which is here translated as gladness:
Gladness is characterized as gladdening (produced by others' success).
Its function resides in being unenvious. It is manifested as the elimination of aversion (boredom). Its proximate cause is seeing beings' success. It succeeds when it makes aversion (boredom) subside, and it fails when it produces merriment.
The Atthasalini (I, Book I, Part V, Chapter XIII, 193) gives a similar definition. The function of sympathetic joy is being unenvious. When others receive gifts or when they are praised envy may arise. The proximate cause of both envy and sympathetic joy is the same: someone else's good fortune. Jealousy arises with the akusala citta which is rooted in aversion, dosa-mua-citta. According to the Visuddhimagga (lX, 100) the far enemy of sympathetic joy is aversion (boredom). If there is wise attention sympathetic joy can arise instead of jealousy. The near enemy of sympathetic joy is "joy based on the homelife"  (Vis. IX, 100). This is joy connected with the "worldly life" of clinging to pleasant sense objects. As we read in the Visuddhimagga, "sympathetic joy fails when it produces merriment", that is, happiness connected with attachment. if there is no right understanding which knows when the citta is kusala citta and when it is akusala citta we may take for sympathetic joy what is actually joy which is akusala. When we say to someone else: "What a beautiful garden you have", there may be moments of sympathetic joy, sincere approval of his good fortune, but there may also be moments with attachment to pleasant objects. Akusala cittas and kusala arise at different moments. Since cittas arise and fall away very rapidly it is hard to know their different characteristics but right understanding of their characteristics can be developed.

     At the moment of sympathetic joy there is also calm with the kusala citta. Those who have accumulation to develop calm can develop calm with sympathetic joy as meditation subject. The Visuddhimagga (IX, 84-124) describes how the divine abiding of sympathetic joy can be developed as a meditation subject of samatha leading to the attainment of jhana (1 With this subject different stages of rupa-jhana can by attained, but not the highest stage. Sympathetic joy can be accompanied by pleasant feeling or by indifferent feeling. It is not the subject of the jhanacittas of the highest stage which are accompanied by indifferent feeling.). it is developed for the purpose of freedom from aversion. When jhana is attained sympathetic joy can be emended to an unlimited number of beings. We read about the development of the four divine abidings in the Digha Nikaya (Dialogues of the Buddha III, no. 33, The Recital, 223, 224):
Four "infinitudes" (appamannas), to wit :- herein, monks, a monk lets his mind pervade one quarter of the world with thoughts of love... pity... sympathetic joy... equanimity, and so the second quarter, and so the third, and so the fourth. And thus the whole wide world, above, below, around and everywhere does he continue to pervade with heart... far-reaching, grown great and beyond measure, flee from anger and ill-will.
Sympathetic joy can be developed in daily life. There are opportunities for its development when we see someone else's good fortune. if we see the disadvantages of jealousy there are conditions for being appreciative when we see that someone is in good health, has success in life and receives honour and praise. We read in the Digha Nikaya (Dialogues of the Buddha III, no. 31, Sigalovada sutta) that the Buddha spoke words of advice to Sigala which were to be applied in daily life. He spoke to him about the characteristics of bad friends and of good friends. As regards the friend who sympathizes, he is to be reckone as as sound at heart on four grounds (187, 25):
... He does not rejoice over your misfortunes: he rejoices over your prosperity: he refrains anyone who is speaking ill of you; he commends anyone who is praising you.
The good friend is not jealous but he rejoices in someone else's good fortune. One can check oneself whether one really is a good friend to someone else. If we are jealous we are not sincere in our friendship.

     If we tend to be jealous it is difficult to cultivate sympathetic joy, since jealousy has been accumulated there are conditions for its arising when we see that someone else receives praise or other pleasant objects. it is useful to realize such moments of jealousy, even when they are not coarse but more subtle. If right understanding is being developed we will see that someone else's success does not belong to a "person", that it is only vipaka which is conditioned by kamma, Thus, jealousy is in fact groundless. When right understanding sees that there are no people, no things which exist, only nama and rupa which arise and fall away, there will gradually be less conditions for jealousy. Envy is one of the "lower fetters" (samyojanas) which are eradicated by the sotapanna. When there is no more jealousy there are more conditions for sympathetic joy, it can gradually become one's nature. The sotapanna is the true friend who sympathizes and is "sound at heart on four grounds". 

Sympathetic joy can arise with the eight types of maha-kusala cittas. it does not arise at all times with these types of citta since there is not always an opportunity for it. Thus, sympathetic joy can accompany the maha-kusala cittas associated with pleasant feeling as well as those associated with indifferent feeling. We should remember that sympathetic joy is different from pleasant feeling. The translation of mudita as sympathetic joy or gladness can mislead us. One can be appreciative of someone's success also with indifferent feeling.

Sympathetic joy does not accompany maha-vipakacittas since it has living beings as object (Vis. IV, 181). It can accompany maha-kiriyacittas. Also arahats emend sympathetic joy to living beings. They have eradicated all akusala and good qualities have reached perfection in them. sympathetic joy can accompany rupa-jhanacittas (1 It can accompany the rupavacara cittas of the first, second and third stage of jhana of the fourfold system (and the fourth stage of the five-fold System), but not those of the highest stage. Thus, sympathetic joy can accompany twelve types of rupavacara cittas in all (Vis IX 111, and XIV, 157, 182. See Appendix 8). Sympathetic joy does not accompany lokuttara cittas since these have nibbana as their object. We read in the Gradual Saying (V, Book of the Elevens, Chapter II, 5, Advantages) about the results of the development of the divine abiding of loving kindness, but actually the other divine abidings, namely compassion, sympathetic joy and equanimity lead to the same benefits (Vis. IX, 83, 87, 90). These benefits are the following:
One sleeps happy and wakes happy; he sees no evil dream; he is dear to human beings and non-human beings alike: the devas guard him; fire, poison or sword affect him not: quickly he concentrates his mind: his complexion is serene: he makes an end without bewilderment; and if he has penetrated no further (to arahatship) he reaches (at death) the Brahma- world...
We read in the Visuddhimagga (IX, 97)  with regard to the four "divine abidings" that loving kindness is developed to ward off ill-will, compassion to ward off cruelty, sympathetic joy to ward off aversion and equanimity to ward off greed or resentment. However, we should realize that defilements cannot be eradicated unless the true nature of realities has been realized. all conditioned realities, even the most excellent qualities, are impermanent, dukkha and anatta. We read in the Gradual Sayings (V, Book of the Elevens, Chapter II, 6, 345) about a monk who has developed the four divine abidings:
Then he thus ponders: This heart's release by amity... by compassion... by sympathy... by equanimity is just a higher product; it is produced by higher thought. Then he comes to know: Now even that which is a higher product, produced by higher thought, is impermanent, of a nature to end. Fixed on that idea he wins destruction of the cankers: of if not that, yet by his passion for dhamma, by his delight in dhamma, by utterly making and end of the five fitters belonging to this world, he is reborn spontaneously, and in that state passes utterly away, never to return (hither) from that world.

I    When someone else is hurt we tend to have unpleasant feeling. Can there be compassion at the same time?
II  By what kinds of feeling can compassion be accompanied? Can one extend loving kindness and compassion at the same time to someone else?
III What is the proximate cause of sympathetic joy?
IV Why is it said that the function of sympathetic joy is being unenvious?
V  Why are loving kindness, compassion, sympathetic joy and equanimity called the "Illimitables"?