I assume you are referring to the following incident related in the Torah:

In the fortieth year of their desert sojourn, the Jews complained regarding the manna, which was the staple of their diet. G‑d regarded this as a “slap in the face,” a demonstration of their lack of appreciation, and dispatched venomous serpents to attack the Israelite encampment. Moses prayed to G‑d on the Jews’ behalf, and G‑d instructed him to make a serpent and place it on a pole. Whoever looked up at this copper serpent was healed (Numbers 21:5–9).

The obvious questions which this story raises: a) Why a snake? b) If a snake has positive healing powers, why did the snake entice Adam and Eve to turn away from G‑d’s commandment? One would certainly not expect the snake to be a source of blessing and healing! What does the serpent represent?

We must begin by emphasizing that it was not the snake itself that brought the cure. In the words of the Talmud: “Could a snake [on a pole] cause death [by not looking at it] or give life [by looking at it]? Rather, when Israel would look upward and subject their hearts to their Father in Heaven, they would be cured; but if not, they would waste away.”

In other words, their healing consisted of comprehending that a Jew’s life transcends the natural order. When looking upward, towards the spiritual worlds, they repented and reaffirmed their trust in G‑d and His healing power, and were cured.

With this in mind, we can understand why the snake was chosen, as this only made things even more supernatural. A venomous snake is a source of harm and destruction. Spiritually, too, the snake brought incredible harm to this world when it enticed Eve to eat from the Tree of Knowledge. Yet here was the image of the harmer that actually healed! Or as the biblical commentator Nachmanides puts it, “A miracle within a miracle.”

This demonstrated how ultimately G‑d is in control over everything, and that He has the ability to bring beneficence or destruction to the world employing any of the creatures he created.

[If we look carefully, we discover that this same method of healing is used elsewhere. Moses used a bitter stick to sweeten bitter waters (Exodus 15:25 and Targum Yonatan there). And it was salt that Elisha used to purify the harmful water (II Kings chapter 2).]

Incidentally, Moses’ copper snake was eventually deified by certain Jews, as they mistakenly believed that it possessed divine healing powers. This led the righteous King Hezekiah of Judah (6th century BCE) to destroy this snake (II Kings 18:4).

Yours truly,

Rabbi Yisroel Cotlar