There are many symbols used in Christian art to depict death, and one of those symbols is a bird flying out of a cage.
This symbol can be seen in a variety of Christian artwork, and is inspired by the following verse from Psalm 68.
Thou didst ascend the high mount,
leading captives in thy train,
and receiving gifts among men,
even among the rebellious, that the Lord God may dwell there.
The image from this Psalm is of God leading the "captives" to the heights of Heaven.
Human life on earth in Christian spirituality is often described as a "prison," and release is sometimes compared to Moses leading the nation of Israel out of the captivity of Egypt, into the Promised Land.
While on earth we are restrained by our bodies and our fallen human nature, in Heaven we will be truly free and fully united with God.
Sometimes death can be viewed in a negative light, but by using the image of a bird flying from a cage, we can see the liberating power of death to unite us to God for all eternity.
