In our earthly lives God works in us; in eternal life God will rest in us, and we in God—although God is “always working and always at rest.” ( Confessions 13.37.52) Because God never ceases to do good, we exist and share in his life. He is peace, and we are called to share in his peace. But how can we know this peace who is the Triune God? Only, Augustine answers, through the receptivity of passionate prayer (see Matthew 7:7–8).

Matthew Levering, The Theology of Augustine: An Introductory Guide to His Most Important Works (Grand Rapids, MI: Baker Academic, 2013), page 110.

My notes: Professor Levering is commenting on St. Augustine’s “Confessions”, book 13, chapter 37, which is at the very end of Confessions. So our coming to know and experience peace can only happen with our receiving peace from God, through our passionate prayer life.