John 17:25

O righteous Father (Pathr dikaie). Nominative form with pathr used as vocative (cf. John 20:28 ), but vocative form dikaie. Then the righteousness of God is appealed to like God's holiness in verse John 11 . The world (kai o kosmo). The translations usually slur over the kai as untranslatable in English. Westcott suggests "while" as a sort of correlative. It is quite possible that here kai is almost concessive like "though" and de=yet: "though the world did not know thee, yet I knew thee, and these knew thee." See Robertson, Grammar, p. 1182 for kai--de--kai and various other uses of kai in John's Gospel.