The journey had been long. After thirty eight years it now appeared as though they were retreating and turning back. The prospect of a long detour drained their spirit and sowed discontent. Now, all of their provisions had been made, but the people complain of their endless days in the wilderness under monotonous and abnormal conditions:Why have you brought us up from Egypt to die in the wilderness? For we have no bread and no water, and our souls are weary of this insubstantial nourishment!
The nourishment that they had been provided with by miracles had become monotonous. G-d’s grace, which had guided them daily for all these years, had become routine. They wanted to reach their destination and grew impatient.
In response, G-d
released the snakes. These snakes were not specially sent. They had always existed in the wilderness. However, until this point, G-d’s Providence had kept them away from the people. For all these ‘monotonous’ years, He had neutralized the venomous fangs of these predators. Now, G-d removed this restraint and the snakes behaved as snakes would naturally behave in the wilderness — they bit the people. The purpose of the snakebites was for the people to realize and appreciate the special protection they had experienced until now. Now they would see the dangers that G-d had spared them from, which lie at every step in the wilderness.
Moshe is instructed to fashion a copper snake and affix it to a tall pole. To be cured from the snakebite, the victim would have only to look upon this snake, to imprint on his mind the image of the snake — the symbol of the perils which G-d spares us from at all times, without our even knowing it. In this way, one will live with the consciousness that every breath of one’s life is a new gift of G-d’s goodness and might.
Rabbi Hirsch concludes his commentary with a timeless message to renew gratitude during moments of discontent:
“A person is capable of reconciling himself to any fate…if only he will regard himself always as one who was saved from danger by G-d’s grace and given back his life as a gift. A person will feel this way if he considers the precipice along whose narrow edge runs the path of all our lives, a precipice which the benevolent G-d screens from our view lest we become dizzy, and over which He carries us in His power and goodness as on eagle’s wings. A person would bless G-d for dealing kindly with him, if he would only see [the venomous snakes] which lurk on our path unseen, and which only G-d’s almighty Providence renders harmless.”
Source: Commentary, Bamidbar 21:4-8