The three metals used in the temple were
They form a hierarchy - for example, Gold is the best metal while
copper is the lowest metal. The copper altar corresponds to
the ordinary people and atones for their sins. The Golden altar
corresponds to the priestly people and addresses their needs.
The Bible does not give us much information on the symbolism of copper,
silver, and gold. It is possible to give various symbolic associations: For
example, copper vessels are used with fire while silver,gold vessels are
more precious and not used with fire. We may therefore say that copper atones
for fiery emotions. Rashi states that Copper atones for brazenness.
Perhaps Rashi focuses on the Hebrew root of copper, Nun-Cheth-Shin which
is also the root of the word snake, which possibly symbolizes brazenness
or similar emotions.
I think it important to emphasize that the symbolic interpretation should
be objective. Therefore we are not focusing on lingual coincidences. We are instead
focusing on something common to all interpretations: Copper, silver, Gold form
a hierarchy of metals. Using this basic idea we symbolically interpret: There
are three stages of people: Ordinary, medium and spiritually advanced corresponding
to copper, silver, and gold. Thus the copper altar atones for the ordinary
people. Such an approach which doesn't emphasize particular traits of ordinary
people - such as brazenness - seems the most acceptable; something that can be agreed
to by all people. That is all people can agree that at least the Bible is
talking about atonment for ordinary people. Then each person can add more
detail such as acts of brazenness. The idea of ordinary could be accepted
by everybody while the focus and specficitiy on particular emotions, like brazenness,
would only be accepted by those people who believe them.