In a sermon on the subject of law and grace, Wayne Thompson, pastor of Sovereign Grace Baptist Church in Rusk, Texas, quoted this wonderful little poem:
"Do this and live!" the law demands,
But gives me neither feet nor hands.
But sweeter sounds the gospel brings,
It bids me fly, and gives me wings!
To my way of thinking, it really captures the contrast.
I have not yet found the proper attribution for it -- I've seen from John Bunyan in the 1600s to John Fischer in the 1970s -- and would be glad to know the author.