John 6:57

καθὼς ἀπέστειλέν με ὁ ζῶν πατὴρ κἀγὼ ζῶ διὰ τὸν πατέρα, καὶ ὁ τρώγων με κἀκεῖνος ζήσει δι' ἐμέ.

Rough Word-by-word:
And as he has sent me the living father also I live for the sake of the father, and the one eating me also this one he will live for the sake of me.

Smooth Translation:
And as the living father sent me, I also live for the sake of the father, and the one who eats me, this one will also live for the sake of me.

Notes:
The implications of the accusative use of the preposition διὰ carry some significance. This is not the genitive use indicating agency ("through," or "by means of"), but rather the accusative, as B. F. Wescott puts it,"describing the ground or object." Some translations render this "for," "by," or "because of."

Jesus is saying here that those who take him into themselves for sustenance will (note the force of the future verb) live for him. As Dr. Gary Staats often says, "If there's fire in the fireplace there ought to be smoke coming out of the chimney."

καθὼς compound conjunction with adverb "and as" or "even as"

ἀπέστειλέν verb aorist active indicative 3rd singular from ἀποστέλλω (I send) "he has sent"

με pronoun accusative 1st singular "me"

ὁ definite article nominative singular masculine "the"

ζῶν present active participle nominative singular masculine from ζάω (I live) "one living"

πατὴρ noun nominative singular masculine "father"

κἀγὼ compound correlating conjunction with pronoun nominative 1st singular "also I"

ζῶ verb present active indicative 1st singular from ζάω (I live) "I live" (note: I don't know why the contraction of ζάω here)

διὰ preposition with accusative "for the sake of"

τὸν definite article accusative singular masculine "the"

πατέρα noun accusative singular masculine "father"

καὶ conjunction "and"

ὁ definite article nominative singular masculine "the"

τρώγων present active participle nominative singular masculine from τρώγω (I eat) "one eating"

με pronoun accusative 1st singular "me"

κἀκεῖνος compound conjunction and demonstrative pronoun nominative singular masculine "and this one"

ζήσει verb future active indicative 3rd singular from ζάω (I live) "he will live"

δι' preposition with accusative "for the sake of"

ἐμέ emphatic pronoun accusative 1st singular "me"