Treasure in Earthen Vessels

What is the significance of the earthen vessel/clay jar in 2 Corinthians 4:7, where Paul talks about the treasure, the light of Christ's gospel?

In 2 Corinthians chapter 4, particularly verses 7-18, the Apostle Paul uses the powerful analogy of "treasure in earthen vessels" to convey profound truths about the Christian life and ministry.