Selfishness...

Selfishness keeps man blind through life.

Bowl of Saki, by Hazrat Inayat Khan
Commentary by Pir-o-Murshid Inayat Khan:

Christ's teaching that man should be kind and charitable, and that of all other teachers who showed humanity the right path, seems to differ from what one sees from the practical point of view which is called common sense; yet according to uncommon sense, in other words super-sense, it is perfectly practical. If you wish to be charitable, think of the comfort of another; if you wish to be happy, think of the happiness of your fellow men; if you wish to be treated well, treat others well; if you wish that people should be just and fair to you, first be so yourself to set an example.

Man's greatest enemy is his ego which manifests itself in selfishness. Even in his doing good, in his kind actions, selfishness is sometimes at work. When he does good with the thought that one day it may return to him and that he may share in the good, he sells his pearls for a price. A kind action, a thought of sympathy, of generosity, is too precious to trade with. One should give and, while giving, close the eyes. Man should remember to do every little action, every little kindness, every act of generosity with his whole heart, without the desire of getting anything in return making a trade out of it. The satisfaction must be in doing it and in nothing else.

Every step in evolution makes life more valuable. The more evolved you are, the more priceless is every moment; it becomes an opportunity for you to do good to others, to serve others, to give love to others, to be gentle to others, to give your sympathy to souls who are longing and hungering for it. Life is miserable when a person is absorbed in himself; as soon as he forgets himself he is happy.

Tulsidas, the Hindu poet, says that the essence of religion is kindness. Those who are inclined to do kindness in life must not discriminate among the people around them, between those to whom they must be kind and those to whom they need not be kind. However kind and good a person may be to those he likes, to those he wishes to be kind to, he cannot for this be called kind by nature; real kindness is that which gushes out from the heart to the worthy and to the unworthy. ... Man is the outcome of the development of the whole of creation; therefore the ego, which makes one selfish, is developed in him more than in any other creature. Selfishness keeps man blind through life, and he scarcely knows when he has caused harm to another. ... In this struggle of life, if a man can be considerate enough to keep his eyes open to all around him and see in what way he can be of help to them, he becomes rich; he inherits the kingdom of God.