There are really two different issues being discussed in this thread — agency and instrumentality. Agency is usually expressed with a preposition + the genitive, instrumentality is usually expressed with the dative, sometimes (and especially in Koine) with the preposition ἐν + dative. Agency is usually personal, instrumentality impersonal. I would take ἐν αὐτῷ with ζωὴ ἦν, which would meant that the λόγος is the source of life.
Statistics: Posted by Barry Hofstetter — September 27th, 2016, 1:53 pm