This one is particularly beautiful and profound, straight from the heart. When I first read it, I loved the fact that he needs solitude and time to think about Milena, but then when I read it the second time, something else struck me: when he says his office job is boring, his flat is stupid, but he feels he must not complain about his everyday reality because Milena is part of it too, and the gratefulness he feels for that: this moment which belongs to you: Letters To Milena

Be not careless in deeds, nor confused in words, nor rambling in thought. Book VIII

If we all got angry together something might be done. The Return of the King

No man really knows about other human beings. The best he can do is to suppose that they are like himself. The Winter of Our Discontent