Since the Law has no more than a reflection of these realities, and no finished picture of them, it is quite incapable of bringing the worshippers to perfection, with the same sacrifices repeatedly offered year after year. Otherwise, the offering of them would have stopped, because the worshippers, when they had been purified once, would have no awareness of sins. Instead of that, the sins are recalled year after year in the sacrifices. Bulls’ blood and goats’ blood are useless for taking away sins, and this is what he said, on coming into the world:

You who wanted no sacrifice or oblation,
prepared a body for me.
You took no pleasure in holocausts or sacrifices for sin;
then I said,
just as I was commanded in the scroll of the book,
‘God, here I am! I am coming to obey your will.’

Notice that he says first: You did not want what the Law lays down as the things to be offered, that is: the sacrifices, the oblations, the holocausts and the sacrifices for sin, and you took no pleasure in them; and then he says: Here I am! I am coming to obey your will. He is abolishing the first sort to replace it with the second. And this will was for us to be made holy by the offering of his body made once and for all by Jesus Christ.

Here I am, Lord! I come to do your will.

I waited, I waited for the Lord
  and he stooped down to me;
  he heard my cry.
He put a new song into my mouth,
  praise of our God.

Here I am, Lord! I come to do your will.

You do not ask for sacrifice and offerings,
  but an open ear.
You do not ask for holocaust and victim.
  Instead, here am I.

Here I am, Lord! I come to do your will.

Your justice I have proclaimed
  in the great assembly.
My lips I have not sealed;
  you know it, O Lord.

Here I am, Lord! I come to do your will.

I have not hidden your justice in my heart
  but declared your faithful help.
I have not hidden your love and your truth
  from the great assembly.

Here I am, Lord! I come to do your will.

Alleluia, alleluia!
Let your face shine on your servant,
and teach me your decrees.
Alleluia!