Law and Grace (again?)

I've gone on about Law and Grace many, many times. But at the risk of beating a dead horse; I was reading the other day and came across this:

It is to be noted that, while the people are distinctly put under law, the principle of the second tables was law after present forgiveness and mercy. This is exactly the ground Christians want to be upon now -- to bring in law after grace and mercy. But this it is Paul calls the ministration of death and condemnation. (J. N. Darby, Synopsis, Exodus, Chapters 35 to 40)