Numbers 21:9

When he beheld the serpent of brass, he lived] rather, 'when he looked to it,' i.e. not casually but of purpose and with faith. The lifeless image of the serpent that had caused the pain and death of so many was a symbol of the victory over these things that God gives to those who trust in Him. The Jewish commentators recognise here an illustration of the power of faith. 'The serpent neither killed nor preserved alive, but if the Israelites lifted up their eyes and turned their hearts to their Father in heaven they were healed; if not, they perished.' Similarly in the book of Wisdom (Numbers 16:6), the brazen serpent is called 'a token of salvation to put them in remembrance of the commandment of Thy law, for he that turned toward it was not saved because of that which was beheld, but because of Thee, the Saviour of all.' The brazen serpent raised upon the pole, for the healing of those who were ready to die, is a striking emblem of the Saviour 'lifted up' on the Cross, for the salvation of all who are wounded by 'that old serpent the devil,' and who look in faith to Him: see John 3:14.

10-15. Journey to the Arnon.