Angels show their love for God through their service of other creatures, just as we are enjoined to show our love for God by serving one another. Angels make God's goodness concrete, both in this life and in the life to come.
Mystery is what happens to us when we allow life to evolve rather than having to make it happen all the time...There is something holy-making about simply presuming that what happens to us in any given day is sent to awaken our souls to something new: another smell, a different taste, a moment when we allow ourselves to lock eyes with a stranger, to smile a bit, to nod our heads in greeting.