The author of Hebrews mentions Jesus as one who is God's Son, and that God has spoken to us in his Son. This is a profound statement because it's contrasted, or set in comparison relationship, to the many ways that God has spoken in the past. So, according to the author of Hebrews then, the fact that God has sent his Son means that he's spoken in a final way or in a more complete way, and here I think we need to understand that there is a progression of God's revelation to us and that there's a culmination point with the coming of Jesus in terms of God representing himself directly in his Son. And what this means, what this means is that there's going to be an end of a certain way of people relating to God, that is, through a cultic system with a temple. And there's a transformation that's taking place. And so, "last days" can be understood in the sense of a closing down of a certain system of relating to God, while God is also opening up a greater, larger, more expansive way that people can relate to God and experience his presence and his Word. And so, specifically, that Word has come in his Son, so God has spoken directly to us now in a Son, and we had better listen to what he has to say for us to continue in relationship with God and to experience the salvation he has to offer us.