Ralph Erskine, a Scottish pastor in the 1700s, wrote a hymn that expresses the relationship between law and gospel. This will preach.
The law supposing I have all,
Does ever for perfection call;
The gospel suits my total want,
And all the law can seek does grant.
The law could promise life to me,
If my obedience perfect be;
But grace does promise life upon
My Lord’s obedience alone.
The law says, Do, and life you’ll win;
But grace says, Live, for all is done;
The former cannot ease my grief,
The latter yields me full relief.
The law will not abate a mite,
The gospel all the sum will quit;
There God in thret’nings is array’d
But here in promises display’d.
The law excludes not boasting vain,
But rather feeds it to my bane;
But gospel grace allows no boasts,
Save in the King, the Lord of Hosts.
Lo! in the law Jehovah dwells,
But Jesus is conceal’d;
Whereas the gospel’s nothing else
But Jesus Christ reveal’d.