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.
Birds inspire and uplift us with their carols... In the muslc of both birds and humans, beauty is "the wine which overflows." When the last lark has fallen silent, something holy will have vanished from the world. The chorus of life will be muted. The cathedral of the earth will have lost its choir.