The refining pot is for silver and the furnace for gold,
But the Lord tests hearts.
A simple contrast is being set up in this proverb. Furnaces and refining pots are the tools used to determining the purity of precious metals. But God only can examine the purity of men's hearts. The word for test is bachan which is usually translated as "prove". It considers the process of determining something's value or worth. The value of a piece of jewelry can be disguised by tarnish, wear, or erosion. However, a man could know for certain the purity of his precious metal if he melted it down- any impurity would rise to the top. Refining metals is an ancient process testing metal is relatively easy if one has the right tools. "But", only the Lord has the ability to test the purity of a man's heart.
It is important to note that the process of testing is not what is in view in the proverb, but rather the ability to test. Although we are called to judge trees by their fruit (Matt. 7:20), we are not called to assess men's hearts: such presumptuous pride is strictly condemned.
"Do not speak against one another, brethren. He who speaks against a brother or judges his brother, speaks against the law and judges the law; but if you judge the law, you are not a doer of the law but a judge of it. There is only one Lawgiver and Judge, the One who is able to save and to destroy; but who are you who judge your neighbor?" (James 4:11-12)
One of the greatest misunderstandings in history was the one that led to the fall of the Roman Republic. Since the reign of the Tarquin II, the Romans loathed the idea of a king. However, this very hatred of monarchy is what led to the destruction of the Republic and the longest lasting absolute monarchy in history.
In the midst of a public debate Tiberius Gracchus, the very popular tribune of the people, sensed that his life was in danger. To warn his followers of the threat he motioned, pointing to his head. His enemies misunderstood this as a request for the people to make him king. They rushed to the senate and declared that Tiberius was requesting the crown. Furious, the senators rushed to the forum. Since the law forbade weapons in the city of Rome, the senators broke up benches and chairs in order use the scraps as clubs. Tiberius tried to flee, but the mob of senators caught him and beat him to death in the midst of the forum. This was the first act of violence against a public official, and gave precedence to waves of bloodshed to follow. This misunderstanding is what gave rise the marriage of violence and politics in Rome. From this point on, whoever had the most might was right.