The roof of any house stands upon the foundations and the rest of the structure. The foundations themselves are laid in order to carry the roof. This is both useful and necessary, for the roof cannot stand without the foundations and the foundations are absolutely useless without the roof – no help to any living creature. In the same way the grace of God is preserved by the practice of the commandments, and the observance of these commandments is laid down like foundations through the gift of God. The grace of the Spirit cannot remain with us without the practice of the commandments, but the practice of the commandments is of no help or advantage to us without the grace of God.
St. Symeon the New Theologian, with thanks to the Balamand Monastery
Slowly, I have begun to understand the truth of this: the old conflict, so dear to those who are grateful that they are not Catholics, between faith and works, is so neatly subverted here. Of course there is no conflict – and grace is the means by which any appearance of conflict is resolved:
But God, who is rich in mercy, out of the great love with which he loved us even when we were dead through our trespasses, made us alive together with Christ—by grace you have been saved—and raised us up with him and seated us with him in the heavenly places in Christ Jesus, so that in the ages to come he might show the immeasurable riches of his grace in kindness towards us in Christ Jesus. For by grace you have been saved through faith, and this is not your own doing; it is the gift of God… (Ephesians 2.5-8)