Charles Spurgeon Commentary Galatians 3:19-22

"What then is the law? It was added because of transgressions, till the seed should come to whom the promise hath been made; [and it was] ordained through angels by the hand of a mediator. Now a mediator is not [a mediator] of one; but God is one. Is the law then against the promises of God? God forbid: for if there had been a law given which could make alive, verily righteousness would have been of the law. But the scriptures shut up all things under sin, that the promise by faith in Jesus Christ might be given to them that believe." — Galatians 3:19-22 (ASV)

Wherefore then serveth the law? It was added because of transgressions, till the seed should come to whom the promise was made; and it was ordained by angels in the hand of a mediator.

Now a mediator is not a mediator of one, but God is one. Is the law then against the promises of God? God forbid: for if there had been a law given which could have given life, verily righteousness should have been by the law. But the scripture hath concluded all under sin,

Or, "shut us all up under sin." The law has come, and proved us all guilty, and shut us all up as in a great prison from which we cannot escape by any power of our own.

It was added because of transgressions, till the seed should come to whom the promise was made; and it was ordained by angels in the hand of a mediator. Now a mediator is not a mediator of one, but God is one. Is the law then against the promises of God?

God forbid: for if there had been a law given which could have given life, verily righteousness should have been by the law. But the scripture hath concluded all under sin, that the promise by faith of Jesus Christ might be given to them that believe.

Paul constantly comes back to this point, that salvation is all of grace, through faith in Jesus Christ.