Dear Nathaniel,
Dear Benjamin,

The question which was raised last night has a very simple,
direct and conclusive answer, which you can read on the Internet at 
https://en.wikipedia.org/wiki/Golden_Rule#
Quite simply: I treat Grandma and I want Grandma to be treated
in the same manner in which I would want to be treated if I were
in her situation.

Love, Jochen