Numbers 21:9 So Moses made a bronze serpent, and put it on a pole; and so it was, if a serpent had bitten anyone, when he looked at the bronze serpent, he lived.
I love the fact that God used a sign of the evil to take away that evil from the Israelite camp.
God wanted people to realise they would be healed just by listening to Him and obeying His command; and not through any physical thing they could do.
A bronze snake can do nothing! It cannot even do harm like a real snake. Yet that is what God chose for the people to look up to.
God wants us to listen to Him and not worry about all the things in this world around us because He is bigger than big!