原文: Psychologically there are two dangers to be guarded against in old age. One of these is undue absorption in the past. It does not do to live in memories, in regrets for the good old days, or in sadness about friends who are deaD、One’s thought must be directed to the future, and to things about which there is something to be done. This is not always easy; one’s own past is a gradually increasing weight. It is easy to think to oneself that one’s emotions used to be more vivid than they are, and one’s mind more keen. …The other thing to be avoided is clinging to youth in the hope of sucking vigour from its vitality. ?Animals become indifferent to their young as soon as their young can look after themselves, but human beings, owing to the length of infancy, find this difficult.