Blessed Theophylact, Archbishop of Ochrid and Bulgaria wrote this in his Explanation of the Gospel of St. John:
John 3:6-8. 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 from above. The wind bloweth
where it willeth, 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. The Lord leads Nicodemus
away from a carnal birth, saying to him, That which is born of the flesh is flesh; and that
which is born of the Spirit is spirit. This means, the man who is born through Baptism is
spiritual, for you should understand spirit here to mean "spiritual." Indeed, the baptized
man does not become divine Spirit, but in the Spirit he is adopted as a son and receives
grace and honor, and is counted worthy to be called spiritual. Seeing that Nicodemus is
still astounded, the Lord says, Marvel not, and then instructs him by an example from the
material world. "The wind [pneuma] bloweth where it willeth. From the wind learn about
something greater than the wind. The wind blows where it wills; you hear its sound, but
you do not know its movement. For it is uncontainable and unrestrained, and by a natural
power can rush in any direction." By saying that the wind bloweth where it willeth, the Lord
does not mean that the wind has a will and can exercise choice, but, instead, that it has an
unhindered power to move in any manner appropriate to its nature. "Therefore, if you do
not understand how and where the wind blows--this spirit subject to the senses--why ask
questions about the regeneration that comes from the divine Spirit? If the wind-spirit
cannot be restrained, you will never be able to subject the grace of the Holy Spirit to the
laws of nature."(3) Let both Macedonius, who contended against the Spirit, and before him,
Eunomius, be put to shame! Macedonius held that the Spirit was a servant, although he
read here that the wind blows where it wills. How much more would the Holy Spirit move
according to Its own authority, and act where and how It wills? Before Macedonius,
Eunomius erred in the same way, saying that the Spirit is a creature, and, even more
impudently, that he, Eunomius, knew God as well as he knew himself. Let him hear this:
"You do not understand known even the movement and the rush of the wind. O wretch,
how dare you say you know the essence of God?
courtesy of Michael