Real knowledge is to know the extent of one's ignorance.
If you try to do too much, you will not achieve anything.
It does not matter how slowly you go as long as you do not stop.
Old age, believe me, is a good and pleasant thing. It is true you are gently shouldered off the stage, but then you are given such a comfortable front stall as spectator.
He who is really kind, can never be unhappy
Shall I tell you what knowledge is? It is to know both what one knows and what one does not know.