The fourth sign of the zodiac is symbolized by the Crab, a water creature that is also capable of walking on land. We know that the crab symbol was placed in the zodiac some five hundred years before Christ. The Chaldeans gave it the name of Cancer, or Crab, because the crab’s backward or oblique movement appeared to represent the Sun’s movement upon reaching this sign. When the Sun reaches the sign of Cancer (around June 21) it seems to remain stationary for a few days. The Sun’s entry into Cancer begins the summer solstice; the very word solstice signifies “the Sun standing still.”

In Egypt, the constellation was called Stars of the Water and was represented by two turtles. (This may have been because the constellation was seen at dawn when the Nile was at its lowest; Nile turtles were rather plentiful at that time of year.) Many astrologers think that Cancer the Crab is a melding of the Egyptian turtles and a Babylonian water creature called Allul, which was apparently a kind of tortoise. All three water creatures—turtles, tortoise, and crab—are similar in important ways. They resemble each other in form, and all
are hard-shelled and move slowly (like the Sun’s movement on entering Cancer).

According to Greek legend, Cancer is the giant crab that attacked the foot of Hercules while he was engaged in battle with the monstrous nine-headed serpent Hydra. Hercules, son of the god Jupiter and a mortal woman Alcmena, had been sent on twelve difficult and heroic undertakings, known as the Twelve Labors of Hercules. One of Hercules’s Labors was to slay the evil serpent Hydra. Hercules was having his hands full as the crab attacked, for every time Hercules cut off one of Hydra’s heads, two more grew in its place.

The crab’s attack on Hercules was instigated by Juno, Jupiter’s jealous wife, who was set on Hercules’s destruction. Unfortunately, the giant crab’s attack sealed its own doom, for Hercules crushed it before proceeding to dispatch the Hydra.

However, legend has it that Juno was grateful for the crab’s attempt to carry out her orders. As a reward for its obedience and sacrifice, she placed the crab’s figure in the heavens along with other heroic symbols.