Kumon Page FI 78a

ところが、お茶を飲んでいたひとりの青年は、このことわざ（”情けは人のためならず”)を、情けをかけると相手がスポイルされてしまうおそれがある、教育上よろしくない、それが”人のためならず”だと思って使っている、おどろくべき新説だが、いっしょにいた数人の若い男女はそれをきいてだれもおかしいという顔をしない。

The other party might be spoilt, and it uses it thinking, it is "Do not become it because of the person" that not is suitably educationally, and however, when mercy is put, it is effective and doesn't have the face that shows of everyone amusing doing of several young men and women who are together it though the new theory for which it should surprise it doing of one young person who was drinking tea this proverb ("Mercy doesn't become it because of the person").

”情けは人のためならず”を、「情けをかけると相手のためにならない」と解することは、筆者にとってどんな説でしたか。

As for "Mercy doesn't become it because of the person", what theory was to understand for the author , saying that "The other party is not benefited when showing mercy"?