The theoretical ship

The KNVTS has a proud tradition to connect its vision on the future with a view on the historic past of shipbuilding practice. Time for the chair of the KNVTS Ship of the Year Committee to take a step back and reflect on the idea of “vision”. Here is the story of the theoretical ship.

This is the first in a series of articles written by Rien de Meij, chair of the KNVTS Ship of the Year Committee and Senior Project Manager Ships at the Maritime Research Institute Netherlands (MARIN). The articles are also published in SWZ|Maritime. This first article was also published in SWZ|Maritime’s January 2020 issue.

The theoretical ship is the ship that is used to sail a journey that is known as a theoria; a “sacred journey” that leads to the achievement of a mystical vision. The traveller on board the ship has a vision both on the ship and on where it’s going.

This idea is captured by the story of the sacred journeys of the mythical king of Athens, Theseus, and by the story of the classical philosopher Socrates. By the second part of the Bronze Age, the Mediterranean is a vibrant place, full of maritime activity, enabling free exchange in knowledge and materials.

The natural drive to look beyond the horizon results in cultural growth, wealth, trade, and migration [1]. The ancient Greek seafarer explores new coastlines and envisages to enter into never-ending dialogue with anyone he meets. This vision comes back to life in the story of the mythical ship in which Theseus sails to Crete and back again.

The theoretical ship is the ship that is used to sail a journey that is known as a theoria; a “sacred journey”

The story is well known. In one of the variants given to us by Plutarch, the dreadful king Minos had set up a custom that at nine-year intervals, seven Athenian boys and seven Athenian girls were to be sent to Crete, basically to serve as dinner for the Minotaur: the half-man, half-bull that lived in the Labyrinths of Knossos [2, 3].

Prince Theseus of Athens, planning to make an end to this awful custom, joins the delegation of boys and girls that was ready to be sent to Crete. With the help of the Cretan king’s daughter Ariadne, Theseus is able to stab the Minotaur in the throat and, subsequently, to strangle him to death. Next, Theseus manages to escape with the famous two-times-seven young people and sails them back to Athens. This heroic act, together with the execution of many other and equally good works, made Theseus the all-time hero of Attica and Athens.

The Athenian youths were said to have vowed to Apollo, that if they were saved from being sacrificed to the Minotaur, they would make an annual sacred journey to Delos. This way, the myth of Theseus’ sacred journey continued to be re-enacted in an Athenian state festival held in honor of Apollo at Delos. The ritualised journey in which the fourteen Athenian youths sailed to Delos and back again, to celebrate that they had been saved was called a theoria. The ship itself became known as the theoretic ship [theoris].

Detail of the François krater: the ship of Theseus (fragment from vase).

Thirty-oared long-ship

The images on the François krater, a famous wine-mixing bowl dated circa 570 BCE – special already for the fact that it was smashed into 638 pieces by a furious museum guard – may give us an idea of the festivity [4]. The figure on the previous page shows the thirty-oared long-ship, or triakóntoros, landing on the beach, stern-first. It is the theoretical ship that sailed every year on its ritualised journey to Delos and back again.

The youths taking part in the re-enactment are shown throwing their hands in the air in praise; another has jumped overboard and swims to the shore. One has debarked and joins the Athenian youths and maidens on land. To the right (not shown) a line of seven youths and seven maidens dance. This dance is commonly, but some say erroneously, taken for the famous Geranos, the Crane Dance [5].

Further to the right side is Theseus, King of Attica, playing a kithara and facing Ariadne who holds a wreath and – to make no mistake about her identity – the ball of twine, given to her by Daedalus, with which she had helped Theseus to find his way out of the Labyrinth [6].

The Theseus ship, possibly named the Delias, was designed for rowing, although sail would have been used in suitable weather. The sternpost of the ship, called aphlaston, is decorated with the shape of two swan’s heads, facing forward [7]. Possibly the swans were sacrificial, their heads impaled to underline the festivity of the event. The prow (not shown) somewhat resembles the gaping snout of a sea monster [ketos], making the ship “huge-hollow” [megakétis naus] [8, 9].

The mast [histós] has been lowered into the stowed position and the crew is standing, ready to debark. The helmsman [kubernetes] sits with his steering oar [pedálion], his face turned around towards land [10]. Above the gunwale [epikenídessi] run two horizontal rails supported by vertical struts. During inclement weather conditions, these rails would be fitted with portable side-screens [parablemata]. The open ship is an áphraktos (unfenced, undefended), while when covered with side screens of white sail [pararrhymata leuka] or rough hide [pararrhymata trichina], it is called “katáphraktos” or “pephragmene” (defended, fenced) [11, 12].

Detail of the “Thera Flotilla Fresco” showing the theoretical ship.

Ship with mast, sail and cabin

An even earlier image of the annual sacred journey to Delos may be portrayed on the miniature frieze known as the “Thera Flotilla Fresco”. The imagery of the Fresco represents a ship procession from a Bronze Age excavation at Akrotiri, on the Greek island Santorini. It was buried by volcanic ash during the Theran eruption, dated around 1627 BCE and was discovered in 1972 by the Greek archaeologist Spyridon Marinatos [13].

For the following description of the depictions, I must borrow from Nagy’s “Socrates in Plato’s Phaedo” [14]. The image on the south wall shows a fleet of seven ships sailing toward their home port, that is, toward the same place from which it had departed. The theoric ship in this image is the small boat with mast and sail, steered by two helmsmen. It is the only ship with a sail.

Located at the stern of each ship is a structure that looks like a cabin [klίsia] with a male figure seated inside each one [15]. Further wall paintings show a variety of close-up pictures of the decorations (semi-circular garlands of flowers) that are attached to the “cabins” located at the sterns of the seven large ships. Nagy: ‘What is being represented in both paintings is a prototype of a theoria in the sense of a ‘sacred journey’ that leads to the achievement of a mystical vision. And that view of that vision is framed by the two semi-circular garlands through which the viewer views what is seen. To borrow from a modern idiom, the vision is viewed “through rose-colored glasses”.

Depiction of the cabin of the theoretical ship, painted on a wall with window.

Ideas that do not die

As said, the ship which sails every year on a ritualised journey to Delos and back, was believed to be the ship on which Theseus had sailed to Delos together with the rest of the young Athenians who had been saved from being sacrificed to the Minotaur. The ship was preserved by the Athenians by taking away the old planks as they decayed and putting in new and stronger timber in their place. The ship became a standing example among the philosophers for the logical question of things that evolve: one side holding that the ship remained the same, and the other contending that it was not the same.

Socrates: ‘Theoretically, it is still the same ship’

One thousand years after the journey of Theseus, the execution of Plato’s Socrates was delayed because this same theoretical ship had to stay in port. The weather was too bad for the ship to leave on its annual trip to Delos and while it was in port, no executions were allowed. When his prosecutors doubt that this ship is the same ship as the ideal ship in which Theseus had sailed to Delos, because every nail and piece of timber has been replaced since, Socrates answers: ‘Theoretically, it is still the same ship’.

After that, the theoretical ship remained the metaphor for ideas that do not die, and the word “theory” started to develop towards its modern meaning. The question of whether an object is still the same object after all its components have been replaced is known as the Paradox of Theseus [16].

Picture (top): Detail of the “Thera Flotilla Fresco” showing the port of departure.

Notes and references

  1. Historical background is based on Wachsmann,S. 2008:The Ancient Greek Ship. Seagoing Ships and Seamanship in the Bronze Age Levant.
  2. Given in Plutarch Theseus 10.1.There are many stories about these matters, and about Ariadne, and they do not necessarily agree. Plutarch. Lives Vol. I.
  3. King Minos was the first who was known to us to have established a thalassocracy. He was not only a boogieman, but also a first man, a son of Zeus, Cretan overlord of the Cyclades. His legacy is that he is a source of good: there is peace, the sea is clean of pirates and he is the first to establish laws. Within this myth of Theseus being a son of Poseidon, Athens entitles herself to the mastery of the sea, which is what happened. By marrying Phaedra, the daughter of Minos, Theseus connects the Athenian future to the Minoan past.
  4. The François krater: Collection: Florence,Museo Archeologico Nazionale.
  5. Teske, R.T. 1970. The Origins of the Goddess Ariadne. Think of a winding, maze-like dance; the never-ending twists and turns follow the lines of the labyrinth, imitating the escape therefrom. Homer mentions a similar dance, but different choreography, in one line with the making of pottery. Homeric Iliad 18.590-607.
  6. The kithara was an ancient Greek musical instrument in the lyre family. The modern word “guitar” stems from kithara.
  7. Swans are sacred to Apollo. Plato Phaedo 84d-85b.
  8. Homeric Iliad 21.22: ‘As when fish flee scared before a huge dolphin [megakétis] and ll every nook and corner of some fair haven.’
  9. Homeric Iliad 8.222: “The huge hull [megakétea]” of Odysseus’ ship.
  10. The word histós, from histasthai “to stand”, is used for anything that stands up vertically (compare “histogram”), but also for the web that is used for weaving text(-ile) which then literally becomes historia. In Homeric poetry the word is used both for the loom of Pênelópê and for the ship’s mast of Odysseus: the captivity of Pênelópê working the loom complementing the immobility of Odysseus fixed to the mast.
  11. The name áphraktos (undefended, not fenced) may be at the origin of our word “frigate”.
  12. Casson L. 2014. Ships and Seamanship in the Ancient World. Princeton University Press. Available online at Project MUSE, Johns Hopkins University Press. Baltimore. Kirk, G.S. “Ships on Geometric Vases”. The Annual of the British School at Athens 44 (1949): 93–153. doi:10.1017/S00682454000 17196.
  13. Marinatos, S.1972.Life and Art in Prehistoric Thera(Proceedings of the British Academy, lvii: Albert Reckitt Archaeological Lecture, 1971). London. Oxford University Press. Strasser, Thomas F. “Location and Perspective in the Theran Flotilla Fresco”, Journal of Mediterranean Archaeology 23.1 (2010) 3–26.
  14. Nagy, G.2013. The Ancient Greek Hero in 24 Hours, “Hour 23:The living word II: Socrates in Plato’s Phaedo”.
  15. Klίsia: a place for lying down or reclining: hence, hut, shed, booth, cot, cabin. The klίsia of Achilles was the place where his ship was beached, at the naustathmon, the harbour of the Achaeans. [Homeric Iliad 8.224, 11.7, Odyssey 14.194; the house of the swine herd Eumaios].
  16. Plutarch Theseus 23.1.


Parts of this story have been published at the online community for Classical Studies of The Center for Hellenic Studies, Harvard University, under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported license. Where possible, the images have been selected from pictures that are freely available with open source or Creative Commons licenses.

  1. François Vase: detail side B: Theseus and the 11 Athenian youths. Author (photo): Egisto Sani, Creative CommonsCC BY-NC-SA 2.0via Flickr.
  2. Thera – Representation of a Minoan Ship/Fleet, Ship procession fresco, part 1, Akrotiri, Greece. Public domain via Wikimedia Commons.
  3. Thera – Representation of a Minoan Ship/Fleet. Ship procession fresco, part 3, Akrotiri, Greece. Public domain via Wikimedia Commons.
  4. Ikrion. Room 4. West wall. H. 1.95, W. 1.98 m. Akrotiri, Thera. By courtesy of The Thera Foundation, Athens, Greece.

Author: Mariska Buitendijk

Mariska Buitendijk is one of SWZ|Maritime's journalists as well as the magazine's copy editor.