The jar of clay is everything 3-dimensional about me. It’s the human side of me, the “will,” the “Eve” part. It’s the me who gets sucked right into that tantalizing taste of the “complete works of good and evil” written in the fruit of the tree of knowledge.
II Corinthians 4:7
But we have this treasure in jars of clay to show that this all-surpassing power is from God and not from us.
The jar of clay is fashioned by the Creator, but until it is filled, it is merely an ornament. It is the ingredients that determine the ultimate value of the jar.
I think of the wedding scene at Cana where Jesus turned huge jugs of water into wine. Only Christ can miraculously change base ingredients to fruitfulness.
Our jars are mere skeletons of who we are meant to be. The outlines. The sketches.
Not until the jars are fired are they ready for use.
Here is the real paradox of the jar of clay: we are filled with all that is good from God and then we are encouraged to pour it out again. From our perspective, it appears the jar will empty, but God continues to fill it. In fact, the stuff gets better with each filling.
Pour Christ in and pass the jug.
Meditations from Zion 
Funny, the first time I read through your inspired post, I completely missed: “Not until the jars are fired are they ready for use”. That is Key! He makes the fragile jar of clay, sturdy and the empty vessel overflowing! Thank You, Lord!
Thanks for reading. I need to remind myself of this truth daily.