The first reading today is from the Book of Numbers 21:4-9:

With their patience worn out by the journey, the people complained against God and Moses, “Why have you brought us up from Egypt to die in this desert, where there is no food or water? We are disgusted with this wretched food!” In punishment the LORD sent among the people saraph serpents, which bit the people so that many of them died. Then the people came to Moses and said, “We have sinned in complaining against the LORD and you. Pray the LORD to take the serpents from us.” So Moses prayed for the people, and the LORD said to Moses, “Make a saraph and mount it on a pole, and if any who have been bitten look at it, they will live.” Moses accordingly made a bronze serpent and mounted it on a pole, and whenever anyone who had been bitten by a serpent looked at the bronze serpent, he lived.

The Book of Numbers is the title of the book in English, but the Hebrew title is, more commonly, bemiḏbar, “in the wilderness [of]”). “In the wilderness” describes the contents of the book much better than “numbers,” which is derived from the censuses described in later chapters. Our passage occurs after God has assigned them to wander in the desert for a generation because of their rebellion against the leadership of God. They seem to have to fight their way through the wilderness.