A house roof is held up by the foundations and the rest of the building, and the foundation and the rest of the building are laid to hold the roof – since both are necessary and useful – and neither is the roof built without the foundations and the rest of the house, nor can foundations and walls without roof make a building fit to live in.
So it is with the soul: the grace of the Holy Spirit is preserved by keeping the commandments, and the keeping of the commandments is the foundation laid for receiving the gifts of God’s grace.
Neither does the grace of the Holy Spirit remain in us without our obeying the commandments, nor can obeying the commandments be useful and salutary without Divine grace.
St. Simeon the New Theologian (Practical and Theological Precepts no. 95, Writings from the Philokalia on Prayer of the Heart; Faber and Faber pg. 119)