Since you are referring to a teaching by The Lord Himself, to Nicodemua, perhaps you should look it up in John 3, and follow the trail back to the Torah and learn the lesson Jesus was teaching? If you need help, there are several on this very thread who would with agape help you. It was a brass snake, btw, lifted up upon a pole.
They were wandering around in the desert somewhere.....where did they come up with the ability to cast a brass snake???