The legend of Cadmus shines as brightly as the heroes who would come after him in the rich tapestry of Greek mythology. This Phoenician prince, renowned for his bravery and strength, stands alongside the likes of Perseus and Bellerophon as one of the greatest slayers of monsters before the advent of Heracles. Cadmus, said to be the son of King Agenor and Queen Telephassa of Tyre, emerged from a lineage tracing back to the powerful deities Poseidon and Libya.

Sent on a mission by his royal parents, Cadmus's initial quest was to retrieve his sister, Europa, who had been abducted by Zeus from the shores of Phoenicia. However, alternative versions of the myth suggest that Cadmus and Europa were the children of Phoenix. Regardless, Cadmus's journey led him to found or refound the city of Thebes, which he named Cadmeia in honor of his own lineage and achievements.

Cadmus's accomplishments extended beyond Thebes. He is also credited with the establishment of cities in Illyria, including Bouthoe and Lychnidus. These foundations, along with the deep-rooted traditions among the Illyrian peoples, demonstrate the lasting impact of Cadmus's presence and his mythical narrative.

The Greek historian Herodotus attributed to Cadmus the introduction of the Phoenician alphabet to the Greeks, who adapted it to create their own Greek alphabet. Modern scholarship widely supports Herodotus's assertion regarding the Phoenician origin of the alphabet. Herodotus placed Cadmus's existence approximately sixteen hundred years before his own time, dating back to around 2000 BC. He encountered the Cadmean writing engraved on tripods in the temple of Apollo at Thebes, which he believed dated back to the era of Laius, Cadmus's great-grandson.

However, there are discrepancies between Herodotus's timeline and the historical development of the Phoenician and Greek alphabets. The earliest Greek inscriptions match Phoenician letter forms from the late 9th or 8th centuries BC. The proper Phoenician alphabet itself emerged around 1050 BC, after the Bronze Age collapse. The absence of writing awareness in Homeric literature further complicates the issue.

The only mention of writing in the Homeric poems refers to "baneful signs," specifically the Bellerophontic letter. This limited literary engagement with writing suggests a decline in the knowledge of the earlier Linear B script during the Dark Age. One theory suggests that the legend of Cadmus introducing the alphabet may be connected to earlier traditions surrounding the origins of Linear B writing in Greece.

According to Greek myth, Cadmus's descendants ruled Thebes for several generations, even during the time of the Trojan War. This lineage further cemented his status as a foundational figure in the city's history and mythology.

Cadmus's travels took him to Samothrace, an island sacred to the "Great Gods" or the Kabeiroi. He was accompanied by his mother, Telephassa, and his nephew or brother, Thasus, who gave his name to the nearby island of Thasos. According to Diodorus Siculus, the trio assumed different names on Samothrace: Electra and her two sons, Dardanos and Eetion or Iasion. 

Harmonia, Electra's daughter, became Cadmus's bride, mirroring the story of Zeus's abduction of Europa. The wedding of Cadmus and Harmonia was a grand affair, attended by all the gods who bestowed gifts upon the couple. Harmonia received a peplos crafted by Athena and a necklace forged by Hephaestus. This necklace, known as the Necklace of Harmonia, would bring misfortune to all who possessed it.

Cadmus's arrival at Delphi marked a turning point in his journey. Consulting the oracle, he was instructed to abandon his original quest and instead follow a special cow with a half moon on her flank. The cow, given to him by Pelagon, the King of Phocis, led him to Boeotia, where Cadmus founded the city of Thebes.

In his quest to sacrifice the cow to Athena, Cadmus faced a formidable water-dragon, reminiscent of the Lernaean Hydra. He defeated the dragon, completing the task of a culture hero. Following Athena's guidance, Cadmus sowed the dragon's teeth into the ground. From these teeth, armed men known as the Spartoi ("sown") emerged. By cleverly causing them to fight amongst themselves, Cadmus ensured that only five survived. These five warriors became instrumental in the construction of the Cadmeia, the citadel of Thebes, and established noble lineages within the city.

Despite his triumphs, Cadmus's life was marred by tragedy. The slaying of the sacred dragon incurred the wrath of Ares, who demanded Cadmus serve him for eight years. It was during this time that Cadmus was joined in marriage to Harmonia. Their union produced a son, Polydorus, and four daughters—Agave, Autonoë, Ino, and Semele. Some accounts even mention six daughters known as the Cadmiades: Ino, Agaue, Semele, Eurynome, Kleantho, and Eurydike. The Necklace of Harmonia, a divine gift, cast a dark shadow over Cadmus's family, leading to their misfortunes and the eventual unrest within Thebes.

In the face of these hardships, Cadmus abdicated his throne in favor of his grandson, Pentheus, and ventured to Illyria alongside Harmonia. There, they fought on the side of the Enchelii, establishing the city of Lychnidos and Bouthoe. However, the weight of his actions lingered, and Cadmus expressed his desire to share the fate of a serpent, the creature he had once slain. The gods granted his wish, transforming both Cadmus and Harmonia into serpents.

In alternative versions of the myth, Cadmus and Harmonia underwent their transformation after death, with their souls transcending to the blissful fields while serpents guarded their tombs. Euripides's "The Bacchae" presents a prophecy from Dionysus, where Cadmus and Harmonia spend a period as snakes before finding peace among the blessed.

The etymology of Cadmus's name remains uncertain, with competing theories attempting to explain its origin. One hypothesis links it to the Phoenician root qdm, meaning "the east." This interpretation aligns with Cadmus's journey from the eastern lands to Greece. Another theory suggests a Greek origin, deriving the name from the word kekasmenos, meaning "excellent." Both interpretations add layers of meaning to Cadmus's character as a heroic figure.

The mythical journey of Cadmus, the hero and founder of Thebes, weaves together elements of bravery, divine intervention, and tragic consequences. His introduction of the Phoenician alphabet to the Greeks and his role in the formation of Thebes solidify his place in history and mythology. The legacy of Cadmus stands as a testament to the enduring power of heroic tales and the profound impact of legendary figures on the cultural tapestry of ancient Greece.