15 Brothers and sisters, let me take an example from everyday life. Just as no one can set aside or add to a human covenant that has been duly established, so it is in this case. 16 The promises were spoken to Abraham and to his seed. Scripture does not say “and to seeds,” meaning many people, but “and to your seed,”[i] meaning one person, who is Christ. 17 What I mean is this: The law, introduced 430 years later, does not set aside the covenant previously established by God and thus do away with the promise. 18 For if the inheritance depends on the law, then it no longer depends on the promise; but God in his grace gave it to Abraham through a promise.
19 Why, then, was the law given at all? It was added because of transgressions until the Seed to whom the promise referred had come. The law was given through angels and entrusted to a mediator. 20 A mediator, however, implies more than one party; but God is one.
One legal issue that I recall being mentioned is that without both parties getting something of value, there is no contract. The "Seed" was able to provide that counter-weight Himself.