A.T. Robertson Commentary John 3:9

"Nicodemus answered and said unto him, How can these things be?" — John 3:9 (ASV)

How? (Πωσ; ) Nicodemus is not helped either by the use of υδωρ or πνευμα to understand δε γεννηθηνα ανωθεν (the necessity of the birth from above or regeneration). He falls back into his "stupid misunderstanding." There are none so dull as those who will not see. Preoccupation prevents insight. Literally one must often empty his mind to receive new truth.