Reading in Numbers 21:5-9 there is a portion of scripture that talks about the brazen serpent (referenced at the bottom of this post). Basically the people get upset for their condition in the desert. Instead of being thankful for their rescue from Egypt, they complain.
God, then, sent “fiery serpents” that bit people, which resulted in death. The people realized they sinned against God and they pleaded to Moses to pray and ask that the serpents be taken away. Moses prays and the Lord instructed him to make a fiery serpent out of bronze and place it on a pole. Anyone who was bitten could look up at the bronze serpent and would live.
No further mention of it is made in the Old Testament until Hezekiah destroys the object becuase people are treating it as a form of idol worship. But even then, there is no explanation as to why this strange method was used for healing.
It is not until we get to the book of John in the New Testament that we get a glimpse of what this means. What is interesting is that I would venture to guess that most people have heard of the famous passage of John 3:16. If we back up a couple of verses into John 3:14-15, this is what it says:
“And as Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up, that whoever believes in Him should not perish but have eternal life.”
The next verse you could probably reherse by heart, John 3:16.
Just as the serpent, a symbol of sin, was raised up to give people life, so was Jesus raised on a cross bearing our sins to give us eternal life.
Jesus can be found all over the Old Testament when you look for him, and the Old Testament is revealed clearly in the New Testament.