Trying to take hold of God's promises without an understanding of His unchanging law is like a jewel without a setting - easily lost or stolen, it can slip from our grasp.
Equally, presenting God's law without His promises and grace is like the setting of a ring or bracelet without the stone - empty and dull, it can be sharp and wounding.
We need both; together they complete each other and display God's beauty, powerfully attracting others.