John 1:31

κἀγὼ οὐκ ᾔδειν αὐτόν, ἀλλ' ἵνα φανερωθῇ τῷ Ἰσραήλ, διὰ τοῦτο ἦλθον ἐγὼ ἐν ὕδατι βαπτίζων

κἀγὼ pronoun - emphatic form of ἐγώ (I) "And I/Even I/I myself"

οὐκ negative particle "not"

ᾔδειν verb pluperfect active indicative 1st singular from εἴδω (I know) "I had known"

αὐτόν pronoun accusative 3rd singular "him"

ἀλλ' conjunction elided from ἄλλα "but"

ἵνα subjunctive conjunction "that"

φανερωθῇ verb aorist passive subjunctive 3rd singular from φανερόω (I reveal/I make known) "he might be revealed"

τῷ definite article dative masculine singular "the"

Ἰσραήλ proper noun dative masculine singular "to Israel"

διὰ preposition accusative "because of"

τοῦτο demonstrative pronoun "this"

ἦλθον verb aorist active indicative 1st singular from ἔρχομαι (I come) "I came"

ἐγὼ pronoun nominative 1st singular "I"

ἐν preposition dative "in"

ὕδατι noun dative neuter singular "water"

βαπτίζων present active participle nominative masculine singular from βαπτίζω (I baptize) "when I was baptizing/baptizing"

Rough Word-by-word:
Even I not I had known him but that he might be revealed the to Israel because of this I came I in water baptizing

Smooth Translation:
Even I had not known him, but that he might be revealed to Israel, I came baptizing in water.

or:

I myself had not known him, but I came when I was baptizing in water, that he might be revealed to Israel.

Notes:
It is interesting to see the passive participle of φανερόω used and reflects, I think, the humility of John the Baptist. It was the one who sent him who was doing the revealing and John the Baptist's reason for living is given by the subjunctive clause.

Could we learn a lesson from John the Baptist and humbly see our purpose for living in revealing Jesus Christ by our lives?