We are selfish when we are exclusively or predominantly concerned with the good for ourselves. We are altruistic when we are exclusively or predominantly concerned with the good of others.

Think how different human societies would be if they were based on love rather than justice. But no such societies have ever existed on earth.

Is it too much to expect from the schools that they train their students not only to interpret but to criticize; that is, to discriminate what is sound from error and falsehood, to suspend judgement if they are not convinced, or to judge with reason if they agree or disagree?

... The person who, at any stage of a conversation, disagrees, should at least hope to reach agreement in the end. He should be as much prepared to have his own mind changed as seek to change the mind of another ... No one who looks upon disagreement as an occasion for teaching another should forget that it is also an occasion for being taught.

Reading a book should be a conversation between you and the author. Presumably he knows more about the subject than you do; if not, you probably should not be bothering with his book. But understanding is a two-way operation; the learner has to question himself and question the teacher, once he understands what the teacher is saying. Marking a book is literally an expression of your differences or your agreements with the author. It is the highest respect you can pay him.

We love even when our love is not requited.

The tragedy of being both rational and animal seems to consist in having to choose between duty and desire rather than in making any particular choice