Jeremiah 18;4

But the vessel that he was making of clay was spoiled in the hand of the potter; so he remade it into another vessel, as it pleased the potter to make.

GOD tells Jeremiah to go down to the potter's house and there HE will let him hear HIS words. Before GOD tells Jeremiah what to say to the house of Israel, HE shows him an example through the potters hands. Israel had sinned greatly against the LORD and were about to be punished severely but GOD makes a final attempt to stay there punishment as we learn later in verse 7-10, 

7 "If at any time I announce that a nation or kingdom is to be uprooted, torn down and destroyed, 8 and if that nation I warned repents of its evil, then I will relent and not inflict on it the disaster I had planned. 9 And if at another time I announce that a nation or kingdom is to be built up and planted, 10 and if it does evil in my sight and does not obey me, then I will reconsider the good I had intended to do for it."

Even though Israel had repeatedly practiced abomonations in the sight of GOD, being all merciful, GOD still gives them a chance to repent. Unfortunately, they didn't and were delivered into the hands of Nebuchadnezzar and the Babylonians. 

We, like the Israelites, are vessels of clay in GOD's hands and by way of the fallen world, have become spoiled but through Jesus Christ, GOD gives us a way to repent and be reshaped by HIS hand into something that pleases our Supreme Potter. GOD's hands are constantly working to shape us into the perfect vessels to enjoy HIS love but most of us continue to collapse in sin and doubt. If we are steadfast in our faith, then even though the potter's wheel may wobble at times, we can ultimately expect to be shaped into beautiful creations, perfect for holding GOD's grace.