What the Picture Shows
The Greek hero Theseus killed a man named Sinis near the beginning of his heroic career, so he was a young man. From this one detail, you can tell that in the accompanying picture of a tondo of Sinis and Theseus, Sinis sports a beard, Theseus, a sword. Generally treated as a villain, Sinis is thought to have lived on the Isthmus of Corinth by the cliffs of Sceiron (Sciron).
What Was the Relationship Between Them?
Sinis may have been related to the royal houses of Corinth and Troezen, home of Theseus, so they may have been relatives. They may also have shared a divine father, Poseidon. Having divine sires helps account for the power and abilities of such heroes as Perseus, Hercules and Theseus. Even though Theseus and Sinis may have been half-brothers through the god or some type of cousin through the earthly lines, there was no love lost between them.
What Was Sinis' Crime?
Sinis was a local terror. He would ask passers-by to help him bend pine trees to the ground, perhaps challenging them to a contest first. He would then bind the loser's wrists to the bent trees. These temporarily bowed-down branches and limbs would then revert to their upright positions. The rapid movement tossed or tore apart and killed the victims.
The Place of Sinis in Theseus' Hero-Career
Theseus encountered Sinis on his journey from Troezen to Athens after he had killed the so-called "club-man" Periphetes (Corynetes, according to Diodorus Siculus) in Epidaurus. He did this by making use of the resources available; in this case the club-man's own club. And so Theseus clubbed the club-man to death. He would later hurl from the cliffs named Sceiron (Sciron) their eponymous villain; he would wrestle to death the deadly wrestler Ceryon; and would stretch on his bed the nasty host Procrustes (Apoollodorus calls him Damastes or Polypemon) who made sure his guests physically fit the dimensions of one or the other of his beds. He repeated his resourcefulness with Sinis. Either Theseus used the pine-bender's own trees to kill him, or Theseus pierced Sinis with a sword he carried -- the sword (and sandals) that Theseus' mortal father had left for him hidden under a rock waiting for him to reach the age and strength a hero attains at maturity.
So far, Theseus' actions seem socially justified, but then Theseus followed in a not so illustrious, but just as common tradition: he ravished Sinis' daughter, Perigune. She later bore a son Melanippus.
An Ancient Account of Theseus and Sinis and Others
"[4.59.2] The first, then, whom he slew was he who was called Corynetes,who carried a korynê, as it was called, or club which was the weapon with which he fought, and with it killed any who passed by, and the second was Sinis140 who made his home on the Isthmus.[4.59.3] Sinis, it should be explained, use to bend over two pines, fasten one arm to each of them, and then suddenly release the pines, the result being that the bodies were pulled asunder by the force of the pines and the unfortunate victims met a death of great vengeance.
[4.59.4] For his third deed he slew the wild sow which ad its haunts about Crommyon, a beast which excelled in both ferocity and size and was killing many human beings. Then he punished Sceiron who made his home in the rocks of Megaris which are called after him the Sceironian Rocks. This man, namely, made it his practice to compel those who passed by to wash his feet at a precipitous place, and then, suddenly giving them a kick, he would roll them down the crags into the sea at a place called Chelonê (Turtle).
[4.59.5] And near Eleusis he slew Cercyon, who wrestled with those who passed by and killed whomever he could defeat. After this he put to death Procrustes, as he was called, who dwelt in what was known as Corydallus in Attica; this man compelled the travelers who passed by to lie down upon a bed, and if any were too long for the bed he cut of the parts of their body which protruded, while in the case of such as were too shot for it he stretched (prokrouein) their legs, this being the reason why he was given the name Procrustes. "
Diodorus Siculus Book IV
"Theseus, Sinis, and the Isthmian Games," by E. M. W. Tillyard. The Journal of Hellenic Studies, Vol. 33, (1913), pp. 296-312.
