This short article on the song O Come, O Come Emmanuel by Michael Kelley has been published a couple of times on his blog and explains the biblical imagery used in the hymn that speak of longing fulfilled.

We are longing for what only Jesus can bring, just as Israel was longing for centuries for the coming of God’s chosen One who would be their deliverer.
And while Israel longed for a physical delivery, we know now that our physical deliverance from circumstantial tribulation is only a shadow of the greater deliverance we need, and therefore the greater longing that permeates every experience of our lives.

Read the whole post at Forward Progress.