St. Barsanuphius the Great ca. 6th cent.
Q: A certain Christ-loving man asked the same Elder: “God has created man free, and He Himself says: Without Me you can do nothing (Jn. 15:5). I ask you, how can one reconcile freedom with the fact that without God one can do nothing?”
A: God created man free so that he might incline toward the good; but inclining toward it by his free will, he is in no condition to perform the good without the help of God, for it is written: It is not of him that willeth, nor of him that runneth, but of God Who showeth mercy (Rom. 9:16) And so, when a man bends his heart towards the good, and calls on the help of God, then God, heeding his good fervor, will grant him strength for doing [good]; and in this fashion there is at the same time both one and the other: both freedom of man, and the help given him from God,; for the good proceeds from God but it is performed through His Saints. And thus God is glorified in all, and glorifies them. (Guidance Toward Spiritual Life: Answers to Questions of Disciples, 770)