# Preposition 'by' means 'because of'?

1. She had done her duty by him
2. She did well by her children

The use of preposition 'by' in the above two sentences sounds to me like it means 'because of'. I coudn't find any meaning of preposition 'by' matching with what I feel. I'm not certain that 'by' in these two sentences means 'because of' or has a close meaning or something. So...

...What is the meaning of 'by' in this situation? Please give me some more examples so that I could get a bigger picture about this case!

• I searched for the exact phrase you asked and found the answer online: forum.wordreference.com/threads/… Oct 28, 2019 at 13:06
• It's much the same as That's fine by me - where the preposition has the sense of about, concerning, with respect to, in regard to, as concerns (often, effectively interchangeable with for). Oct 28, 2019 at 13:55
• It can be used in that sense: 'By Pythogoras, we know that the hypotenuse of a right-angled triangle, with sides of length 3 and 4, is 5.' This says that because of Pythogoras' theorem we can calculate this. It's understandable, I think, but not that common. Oct 28, 2019 at 15:17
• @simonatrcl: I'd say your Pythagoras example is just the very common by = via / through / using sense - it's just that at the semantic level it could also make sense with by = because (except in reality that's not implicit in the preposition - it's just in the context itself). Oct 28, 2019 at 15:51
• I would say that on behalf of is more equivalent than because of. Oct 29, 2019 at 2:47

``````She did right by him.