(1) The word that came to Jeremiah from the LORD:
(2) "Come, go down to the potter's house, and there I will let you hear my words."
(3) So I went down to the potter's house, and there he was working at his wheel.
(4) The vessel he was making of clay was spoiled in the potter's hand, and he reworked it into another vessel, as seemed good to him.
(5) Then the word of the LORD came to me:
(6) Can I not do with you, O house of Israel, just as this potter has done? says the LORD. Just like the clay in the potter's hand, so are you in my hand, O house of Israel.
Jeremiah went to the potter's house and witnessed the affects of an impure clay in a potter's hand. The potter had to rework the clay into a different type of vessel, probably after removing the impurity our making a vessel that might be able to be of a different quality using the impure clay. Perhaps it was as simple as adding more water. The idea God wants Jeremiah to take away is that God is making something with someone and if that someone is impure, God can still use them. Of course we see that the certain someone is Israel. Verse 6 states just that, "Can I not do with you, O house of Israel, just as this potter has done? says the LORD. Just like the clay in the potter's hand, so are you in my hand, O house of Israel."
Jeremiah 18:7-11 NRSV
(7) At one moment I may declare concerning a nation or a kingdom, that I will pluck up and break down and destroy it,
(8) but if that nation, concerning which I have spoken, turns from its evil, I will change my mind about the disaster that I intended to bring on it.
(9) And at another moment I may declare concerning a nation or a kingdom that I will build and plant it,
(10) but if it does evil in my sight, not listening to my voice, then I will change my mind about the good that I had intended to do to it.
(11) Now, therefore, say to the people of Judah and the inhabitants of Jerusalem: Thus says the LORD: Look, I am a potter shaping evil against you and devising a plan against you. Turn now, all of you from your evil way, and amend your ways and your doings.
The LORD continues to speak to Israel through Jeremiah; you are a clay vessel that I am shaping with an evil (calamity) intent because you have not obeyed My words! God declares in the previous verses that God will repent, or change His mind, depending on the actions of nation concerned. Does this imply God's judgments are not set in stone? Does it say that God can change His mind? Yes to both, and more. Regardless of the condition of the clay, God can rework it for good. Israel's evil ways can be changed and God will rework the clay of calamity into a clay of beauty. The outcome depends not on God the potter, but Israel the vessel. Unfortunately the vessel has made up its mind in verse 12, "But they say, "It is no use! We will follow our own plans, and each of us will act according to the stubbornness of our evil will."
Jeremiah is next told to bring a clay pot to the Potshard gate which overlooked the Valley of the Sons of Hinnom, or Topeth (later called Gehenna in the Greek) and to break the pot. Several men of the temple were to accompany Jeremiah to hear of the prophecy that would come to pass due to Israel harden hearts witnessed to in verse 11. The Potshard gate was were broken pottery was taken and piled up like a garbage dump. Potshard pile were used by the people to find usable pieces of broken pottery. Job used a potshard to scrape his sores. According to Isaiah 30:14 pieces that were big enough could be used to removes coals from a fire or as a dipper or ladle for scooping water out of the cistern. Some shards might be used to write on as well.
Jeremiah 19:1-6 NRSV
(1) Thus said the LORD: Go and buy a potter's earthenware jug. Take with you some of the elders of the people and some of the senior priests,
(2) and go out to the valley of the son of Hinnom at the entry of the Potsherd Gate, and proclaim there the words that I tell you.
(3) You shall say: Hear the word of the LORD, O kings of Judah and inhabitants of Jerusalem. Thus says the LORD of hosts, the God of Israel: I am going to bring such disaster upon this place that the ears of everyone who hears of it will tingle.
(4) Because the people have forsaken me, and have profaned this place by making offerings in it to other gods whom neither they nor their ancestors nor the kings of Judah have known, and because they have filled this place with the blood of the innocent,
(5) and gone on building the high places of Baal to burn their children in the fire as burnt offerings to Baal, which I did not command or decree, nor did it enter my mind;
(6) therefore the days are surely coming, says the LORD, when this place shall no more be called Topheth, or the valley of the son of Hinnom, but the valley of Slaughter.
Chapter 19 of Jeremiah tells us why judgment was coming. The people had forsaken the LORD and turned to other gods. They also offered their children as live burned offerings which God states never entered His mind, that is to burn anyone alive (think burning in a fictional place called hell). Notice that the valley will no longer retain its given names. What is to happen in this valley to the people of Israel will be a terrible thing that will be remembered for generations to come. In fact Jesus, during his earthly ministry will use it as an example for the hypocritical pharisees. Though modern Christianity have taken Jesus' statements to the pharisees to describe "hell", the pharisees did not understand His words in such a way; they knew what happened in Gehenna.