In plain words
When he will not agree to it, this friendship may again break apart. That is why friendship becomes lasting only when you make friends with those whose age, position, wealth, education and such circumstances are equal to yours.
Next, karuṇā. We should not spread this karuṇā about as we please. We must show karuṇā to those smaller than ourselves. We must show karuṇā only to those who stand at a lower level than ourselves in age, in wealth, in body, in education and in their circumstances too. Only then does this karuṇā gain in value. The standing of karuṇā grows strong too.
Next, muditā. Muditā means this: many people are somewhat above us. We must rejoice at seeing those who are above us. When we see a person better off than we are in health, we must rejoice. We must rejoice at seeing those blessed with greater riches than ours. We must rejoice at seeing officers who hold higher positions than ours. We must rejoice at seeing a person who gets better marks than we do. So muditā is just this: rejoicing at those above us without being jealous and without letting in any other kind of ill feeling.
Next, upekṣā. People speak of apekṣā and upekṣā. Apekṣā means liking; upekṣā means not liking. We should not like those who do evil at all. When we see people who do harm to others, we should not like them. We should not take people who move about with evil minds, wicked plans, bad conduct and evil thoughts as friends at all, nor accept them. We should not like at all those who have bad qualities, wicked plans and bad conduct. When we put these four into practice well, there are no puruṣārthas greater than these. Making friends with one who is our equal, showing karuṇā to one who is lower, rejoicing at the superiority of one who is higher, keeping far away from wrongdoers: these four alone are the true puruṣārthas.
We are not conducting ourselves well and properly in these puruṣārthas. That is why our condition is going downhill. A student, or anyone else, must try to keep the clothes he wears, the ornaments he wears and his own body clean at all times.