One time at our Friday morning men’s Bible study, we were talking about the Final Judgment and how lots of biblical texts speak of how we will be judged by our works. The discussion naturally centered on the relationship between faith and works (or, you could say, between the root and the fruit).
Root and fruit. It's a common analogy. The fruit evidences the life and health of the root. If there is no fruit, then there is a systemic problem. You can't just tack on fruit. You need organic change at the root level.
Jesus [said], "If anyone thirsts, let him come to me and drink. Whoever believes in me, as the Scripture has said, 'Out of his heart will flow rivers of living water.'"