Not destroying, but fulfilling the Law

“Do not think that I came to destroy the Law or the Prophets. I did not come to destroy but to fulfill. For assuredly, I say to you, till heaven and earth pass away, one jot or one tittle will by no means pass from the law till all is fulfilled. Whoever therefore breaks one of the least of these commandments, and teaches men so, shall be called least in the kingdom of heaven; but whoever does and teaches them, he shall be called great in the kingdom of heaven. For I say to you, that unless your righteousness exceeds the righteousness of the scribes and Pharisees, you will by no means enter the kingdom of heaven."

My initial thought is that having told the disciples that they are light, he now goes on to tell them what they need to do to shine. That is not quite accurate, because of course light can’t help but shine. And he is pretty adamant that what he’s about to describe is not really possible for them to do… at least, that is how I always interpreted the line about the scribes and the Pharisees. So, I think what follows is a description of what shining is, of what it looks like. First of all, he relates it to the Law they are used to living under. The old law was something that one did, the new is something that one is. I think that is why he says he didn’t come to destroy but to fulfill. That is, he didn’t come to give a new law, one that was different from the old and made you forsake it. Instead, he came to change people to become more like God, and people that are more like God will fulfill the intent of the Law he created.

I wonder what he means by “these commandments”: the ones they know, or the ones he is about to give them? I feel like he is talking about the ones they know, the Law. That is, they must not think that the Law is less important or that he is saying it is wrong, but that it isn’t what saves and changes them.