Robertson's Word Pictures of the New TestamentJohn 3:4
Being old (gerwn wn). Nicodemus was probably familiar with the notion of re-birth for proselytes to Judaism for the Gentiles, but not with the idea that a Jew had to be reborn. But "this stupid misunderstanding" (Bernard) of the meaning of Jesus is precisely what John represents Nicodemus as making. How "old" Nicodemus was we do not know, but surely too old to be the young ruler of Luke 18:18 as Bacon holds. The blunder of Nicodemus is emphasized by the second question with the mh expecting the negative answer. The use of deuteron adds to the grotesqueness of his blunder. The learned Pharisee is as jejune in spiritual insight as the veriest tyro. This is not an unheard of phenomenon.