John 3:6 - Coke's Commentary on the Holy Bible

That which is born of the flesh is flesh;— That Nicodemus might see the absurdityof his notion, Jesus told him, that whatsoever is begotten, must necessarily partake of the nature of that which begets it; and therefore, that a man's being begotten and born a second time by his natural parents, were that possible, would not make him holy, or qualify him for the kingdom of God. After such a second generation, his nature would be the same sinful and corrupt thingas before, because he would still be endued with all the properties and sinful inclinations of human nature; and consequently would be as far from a happy immortality as ever:—That which is born of the flesh is flesh:—But that which is born of the Spirit is Spirit: spiritual, heavenly, divine, like its author.