Jupiter, under the disguise of a bull, had carried away Europa, the daughter of Agenor, king of Phoenicia. Agenor commanded his son Cadmus to go in search of his sister, and not to return without her. Cadmus went and sought long and far for his sister, but could not find her, and not daring to return unsuccessful, consulted the oracle of Apollo to know what country he should settle in. The oracle informed him that he should find a cow in the field, and should follow her wherever she might wander, and where she stopped, should build a city and call it Thebes. Cadmus had hardly left the Castalian cave, from which the oracle was delivered, when he saw a young cow slowly walking before him. He followed her close, offering at the same time his prayers to Phoebus. The cow went on till she passed the shallow channel of Cephisus and came out into the plain of Panope. There she stood still, and raising her broad forehead to the sky, filled the air with her lowings. Cadmus gave thanks, and stooping down kissed the foreign soil, then lifting his eyes, greeted the surrounding mountains. Wishing to offer a sacrifice to Jupiter, he sent his servants to seek pure water for a libation. Near by there stood an ancient grove which had never been profaned by the axe, in the midst of which was a cave, thick covered with the growth of bushes, its roof forming a low arch, from beneath which burst forth a fountain of purest water. In the cave lurked a horrid serpent with a crested head and scales glittering like gold. His eyes shone like fire, his body was swollen with venom, he vibrated a triple tongue, and showed a triple row of teeth. No sooner had the Tyrians dipped their pitchers in the fountain, and the in- gushing waters made a sound, than the glittering serpent raised his head out of the cave and uttered a fearful hiss. The vessels fell from their hands, the blood left their cheeks, they trembled in every limb. The serpent, twisting his scaly body in a huge coil, raised his head so as to overtop the tallest trees, and while the Tyrians from terror could neither fight nor fly, slew some with his fangs, others in his folds, and others with his poisonous breath.
Cadmus, having waited for the return of his men till midday, went in search of them. His covering was a lion's hide, and besides his javelin he carried in his hand a lance, and in his breast a bold heart, a surer reliance than either. When he entered the wood, and saw the lifeless bodies of his men, and the monster with his bloody jaws, he exclaimed, "O faithful friends, I will avenge you, or share your death." So saying he lifted a huge stone and threw it with all his force at the serpent. Such a block would have shaken the wall of a fortress, but it made no impression on the monster. Cadmus next threw his javelin, which met with better success, for it penetrated the serpent's scales, and pierced through to his entrails. Fierce with pain, the monster turned back his head to view the wound, and attempted to draw out the weapon with his mouth, but broke it off, leaving the iron point rankling in his flesh. His neck swelled with rage, bloody foam covered his jaws, and the breath of his nostrils poisoned the air around. Now he twisted himself into a circle, then stretched himself out on the ground like the trunk of a fallen tree. As he moved onward, Cadmus retreated before him, holding his spear opposite to the monster's opened jaws. The serpent snapped at the weapon and attempted to bite its iron point. At last Cadmus, watching his chance, thrust the spear at a moment when the animal's head thrown back came against the trunk of a tree, and so succeeded in pinning him to its side. His weight bent the tree as he struggled in the agonies of death.
While Cadmus stood over his conquered foe, contemplating its vast size, a voice was heard (from whence he knew not, but he heard it distinctly) commanding him to take the dragon's teeth and sow them in the earth. He obeyed. He made a furrow in the ground, and planted the teeth, destined to produce a crop of men. Scarce had he done so when the clods began to move, and the points of spears to appear above the surface. Next helmets with their nodding plumes came up, and next the shoulders and breasts and limbs of men with weapons, and in time a harvest of armed warriors. Cadmus, alarmed, prepared to encounter a new enemy, but one of them said to him, "Meddle not with our civil war." With that he who had spoken smote one of his earth-born brothers with a sword, and he himself fell pierced with an arrow from another. The latter fell victim to a fourth, and in like manner the whole crowd dealt with each other till all fell, slain with mutual wounds, except five survivors. One of these cast away his weapons and said, "Brothers, let us live in peace!" These five joined with Cadmus in building his city, to which they gave the name of Thebes.
Cadmus obtained in marriage Harmonia, the daughter of Venus. The gods left Olympus to honor the occasion with their presence, and Vulcan presented the bride with a necklace of surpassing brilliancy, his own workmanship. But a fatality hung over the family of Cadmus in consequence of his killing the serpent sacred to Mars. Semele and Ino, his daughters, and Actaeon and Pentheus, his grandchildren, all perished unhappily, and Cadmus and Harmonia quitted Thebes, now grown odious to them, and emigrated to the country of the Enchelians, who received them with honor and made Cadmus their king. But the misfortunes of their children still weighed upon their minds; and one day Cadmus exclaimed, "If a serpent's life is so dear to the gods, I would I were myself a serpent." No sooner had he uttered the words than he began to change his form. Harmonia beheld it and prayed to the gods to let her share his fate. Both became serpents. They live in the woods, but mindful of their origin, they neither avoid the presence of man nor do they ever injure any one.
There is a tradition that Cadmus introduced into Greece the letters of the alphabet which were invented by the Phoenicians. This is alluded to by Byron, where, addressing the modern Greeks, he says:
"You have the letters Cadmus gave, Think you he meant them for a slave?"
Milton, describing the serpent which tempted Eve, is reminded of the serpents of the classical stories and says:
... "--pleasing was his shape, And lovely never since of serpent kind Lovelier; not those that in Illyria changed Hermione and Cadmus, nor the god In Epidaurus"
For an explanation of the last allusion, see Oracle of Aesculapius, p. 298.