Jesus knowing that the Father had given all things into his hands, and that he was come from God, and went to God; He riseth from supper, and laid aside his garments; and took a towel, and girded himself. (John 13:3-4, KJV)
Periodic sentences are usually dramatic, but John employs that syntax here to create a kind of dramatic irony. The immediate irony, of course, is the grandeur of the phrases followed by the servility of the clause. Jesus’ grand knowledge followed by his servile act. Luke achieves the same immediate irony in a periodic sentence:
Now in the fifteenth year of the reign of Tiberius Caesar, Pontius Pilate being governor of Judaea, and Herod being tetrarch of Galilee, and his brother Philip tetrarch of Ituraea and of the region of Trachonitis, and Lysanias the tetrarch of Abilene, Annas and Caiaphas being the high priests, the word of God came unto John the son of Zacharias in the wilderness. (Luke 3:1-2, KJV)
Luke’s periodic sentence sets John the Baptist’s humble introduction in a time defined by all of the grand layers of government to which John was subject. John’s very introduction, then, foreshadows his later problems with the authorities. Anyway, Luke’s periodic sentence, like John’s, leads us from grandeur to humility. And as in John, the phrases are the clause’s foil.
I like this definition of dramatic irony:
Dramatic irony is when the words and actions of the characters of a work of literature have a different meaning for the reader than they do for the characters. This is the result of the reader having a greater knowledge than the characters themselves.
In John’s periodic sentence, we finally learn the extent of what Jesus understands about himself. But in the sentence’s clause, Jesus acts contrary to it. When John unveils, we find a veil. Luke’s periodic sentence, as deftly as it introduces the tension of John the Baptist’s life, doesn’t pull off what John does here.
John’s surface irony (grandeur/servility) points to a greater dramatic irony, and an inverted one: the reader has a lesser, not greater, “knowledge than the characters themselves.” Therefore, the reader remains the unknown character, maybe more than in a Calvino novel.