Read Numbers 21:4-9
4 The Israelites left Mount Hor by the road that leads to the Gulf of Aqaba, in order to go round the territory of Edom. But on the way the people lost their patience 5and spoke against God and Moses. They complained, “Why did you bring us out of Egypt to die in this desert, where there is no food or water? We can’t stand any more of this miserable food!” 6Then the Lord sent poisonous snakes among the people, and many Israelites were bitten and died. 7The people came to Moses and said, “We sinned when we spoke against the Lord and against you. Now pray to the Lord to take these snakes away.” So Moses prayed for the people. 8Then the Lord told Moses to make a metal snake and put it on a pole, so that anyone who was bitten could look at it and be healed. 9So Moses made a bronze snake and put it on a pole. Anyone who had been bitten would look at the bronze snake and be healed.
This is such a strange passage - the bronze snake was eventually destroyed by Hezekiah (2 Kings 18:4) because it became an object of idolatry.
John compares this to looking at Christ on the cross - the amazing power of knowing God's love.
Lord, help me to see you - and have faith in your love and power.