“And you shall make the altar of acacia wood…and you shall overlay it with copper.” This altar, which stood in the courtyard of the Tabernacle, has a number of different names: the copper altar, the altar of ascent offering, and the outer altar. Though the laver and its pedestal were also made of copper, only the outer altar was named for its copper. It is the main vessel in the Tabernacle that was made of copper. Rashi notes that because of this, the sages learned that the copper altar atones for brazenness (which is related to brass, an alloy made of copper).
The copper altar is where the main service of the Tabernacle—the offering of the communal and personal sacrifices—took place daily. The outer altar symbolizes the rectification of the external dimension of an individual’s character. It is of his external character that an individual is self-conscious and that strengthens the ego with all its crudeness and brazenness. The outer altar thus suggests that we must give this part of ourselves up and sacrifice it to God, on a daily basis. This is the rectification of brazenness.
The Hebrew word for copper (or brass) is nechoshet, which shares a root with the word nachash, snake, which is why the snake that Moses made was also made of copper. The primordial snake caused Adam to sin and as a result, we humans are described as having an external snakeskin (mashcha dechivya), referring to our coarse and unrefined character traits that are driven by our overpowering sense of self and selfishness. All of this was rectified by the copper altar.
The numerical value of “copper altar” (מִזְבַּח הַנְּחֹשֶׁת) is the same as, ”Love your neighbor as yourself” (וְאָהַבְתָּ לְרֵעֲךָ כָּמוֹךָ). “Love your neighbor as yourself” is a major Torah principle and the foundation of the service of self-rectification. The numerical value of “copper altar” also equals the phrase, “Know before whom you stand” (דַּע לִפְנֵי מִי אַתָּה עוֹמֵד)—the state of consciousness that accompanies all service of God.
. Exodus 27:1-2.