"in an old man" and "in him"

Some old people are oppressed by the fear of death. In the young there is a justification for this feeling. Young men who have reason to fear that they will be killed in battle may justifiably feel bitter in the thought that they have cheated of the best things that life has to offer. But in an old man who has known human joys and sorrows, and has achieved whatever work it was in him to do, the fear of death is somewhat abject and ignoble…

–BERTRAND RUSSELL How to grow old from Portraits from Memory

This use of “in” seems a bit odd to me. I feel “for” sounds much better than “in” here. I hope to hear native English teachers’ explanation. Thanks in advance.


‘In’ is fine. The fear of death in an old man.