Pray the LORD to take the serpents away from us.”
So Moses prayed for the people, and the LORD said to Moses,
“Make a saraph and mount it on a pole,
and whoever looks at it after being bitten will live.”
-- Nm 21:4-9
... already in the Old Testament, God ordained or permitted the making of images that pointed symbolically toward salvation by the incarnate Word: so it was with the bronze serpent, the ark of the covenant, and the cherubim.
-- CCC 2130