Verse 4 How can a man, &c. We are not to suppose that Nicodemus seriously understood our Lord as using the language in its literal signification; but, not knowing precisely what he did intend, he employs these expressions as an emphatic mode of asking an explanation. In fact, the Savior's reply seems to indicate, not so much that Nicodemus misunderstood what he meant to say, as that he was our surprised at its extraordinary import. John 3:5 Of water and of the Spirit. Water is emblematical of the public profession of repentance, and the Spirit is the agent that produces the inward change. The meaning, therefore, is, that an entire change in the spiritual condition of the soul must be openly avowed and truly experienced, to fit the sinner for the kingdom of heaven.