Haymo of Halberstadt
Catena Aurea · Johannesevangelium 3
Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother’s womb, and be born? Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God. That which is born of the flesh is flesh; and that which is born of the Spirit is spirit. Marvel not that I said unto thee, Ye must be born again. The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth; so is every one that is born of the Spirit.
(Hom. in Oct. Pent.) But Nicodemus being unable to take in so great and deep mysteries, our Lord helps him by the analogy of our carnal birth, saying, That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. For as flesh generates flesh, so also doth spirit spirit.