In the passive voice "by" introduces the noun doing the "agentive" action in the sentence. The grammatical subject is the "theme" or the patient.
agent = actor, patient = what is acted upon, theme = topic
- This book was written by Charlotte Brontë.
- The results of the older study have been replicated by several more recent ones.
- Did you have to help your son with his homework or did he do it by himself?
- Little has been written by mainstream sources about the question.
- Income taxes must be filed in the US by April 15th
- We need get this fixed by the end of the day.
- The mail usually gets here by noon.
Locative: along / via / near / next to
- I live by the river.
- I live by the school.
- We were sitting by the exit, so we could get back out quickly.
"Means" argument, answers the question how?
(fr. complement circonstantiel de moyen / instrument, etc.)
- By rearranging the seats, the bride kept the feuding uncles as far apart as she could.
- We reached them by phone.
- The video was subtitled by machine.