God told a dying nation to look at a serpent lifted on a pole and live. Jesus told Nicodemus that pole was a preview of His cross.
The Shadow
The snakes came because they complained, and many in Israel were dying with the poison already in their veins. God's solution was strange: He did not remove the snakes or reverse the bites. He told Moses to lift a bronze serpent on a pole, and everyone who looked at it lived. Not working, not earning, not crawling to the pole to prove they were sorry. Looking. Life for a look.
Every detail preaches. Bronze is the Old Testament's metal of judgment, the metal of the altar. And the shape is a serpent, the oldest symbol of sin in the Bible. The image of the very thing that was killing them was fashioned into the instrument of their healing, lifted up and bearing the judgment.
The Fulfillment
Fifteen hundred years later, Jesus interpreted the image Himself, at night, to Nicodemus: “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.” Same pole, same posture, same mechanism, different scale. Paul supplies the theology: He made Him who knew no sin to be sin for us. The judgment left the camp and landed on the One on the pole, and the dying could look and live. And this healing does not wear off by morning like manna. It is eternal life.
Him All Along
Religion hands the poisoned a treatment plan: pray more, confess more, extract the venom yourself. God said something else to the dying: stop staring at the wound and look at the provision. You do not need to catalog every sin to be forgiven of it, or measure the depth of the poison to qualify for the cure. Hebrews uses the same posture for the whole Christian life: looking unto Jesus, the author and finisher of our faith. Everyone who looks, lives. That has not changed.