Q. Why was the serpent (Num. 21) made of brass? What brass? There was none then. What may be the teaching of it, whatever it may be?
A. It is “copper” or native brass: not what we term the latter, which is a mere alloy of copper and zinc of considerably little comparative value compared with copper.
I think we learn its typical import from the symbolic meaning of copper (brass), as used in making the brazen altar and the like. While gold symbolizes the righteousness of God, brass is typical of that righteousness in which God deals with man as a responsible being. Thus in a “serpent” we have portrayed the subtlety of sin — Christ was made “sin for us” (2 Cor. 5:2121For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him. (2 Corinthians 5:21)), and “of brass,” Christ bearing the responsibility of man in judgment, as lifted up on the cross. The mercy seat was gold.