An ancient computer, in Athens

Sometime before 50 B.C.E., a 300-ton ship laden with spoil for Rome set out, probably from the port of Rhodes. It sank in Greek waters off Antikythera, an island otherwise unknown to history, and lay there for two millennia until it was discovered by sponge divers in October 1900. The local prefect informed Athens of the find in an elegant, flowing hand, and an expedition was organized that marked the beginning of indigenous Greek archaeology.

Over the next eight decades, a giant haul was recovered; Jacques Cousteau led the 1978 mission. Among the treasures, including the usual statuary, pottery, coinage, jewelry and glassware, was a mysterious device called, for lack of a better name, the Antikythera Mechanism. Even in the age of the Industrial Revolution, it was a puzzle whose full decipherment would take a century. It turned out to be, in modern terms, the world's oldest surviving analog computer.

The Mechanism, as recovered, was smashed, scattered and deeply corroded. Of its now 82 recognized fragments, most were small, some pebble-sized. They were recovered only in the course of repeated dives, and the fact that they belonged to a single object was only gradually realized.

That this object was a machine was even more slowly perceived. A researcher, Valerios Stais, recognized the outline of a gear on the largest fragment in 1902, but a half-century passed before a British physicist, Derek J. de Solla Price, understood that the fragments were all part of an extraordinarily complex and sophisticated astronomical device whose existence was unsuspected in the ancient world and whose like wouldn't be seen in the West until the orreries of the 17th Century.

Instruction manual

True, you can find scattered references in ancient texts to ingenious devices by Archimedes and other inventors, not to mention Homer's Trojan Horse. But no one could do more than conjecture as to their possible design and use.

One of the astonishing discoveries about the Antikythera Mechanism is that it contains its own engraved instruction manual, in demotic Greek. The problem was that, like the rest of the Mechanism, the text was broken up in various fragments, and thus presented the same reassembly problems as the device as a whole.

What's more, some of what could be seen as writing was corroded to the point of illegibility. Not until the development of x-ray tomography could this material be scanned, and we can now read 95% of the 2,160 extant characters of text.

De Solla Price made the first attempt to fully replicate the Mechanism, but he lacked all the gears and a great deal of the written information, and could never get his machine to work. Fifty years passed before another British scientist, Michael Wright, produced a working model.

Several others have tried their hands as well. Their models, plus all the fragments themselves, are now on display in the superb exhibit of the Antikythera hoard at the National Archaeological Museum in Athens. These uniformly elegant models must be considered works of art in themselves, as well as achievements of reconstructive design.

Like the Mona Lisa?

The original Mechanism, although almost certainly not unique, was no doubt an even more artful wonder. Michael Edwards of Cardiff University goes a bit over the top when he remarks, "In terms of historic and scarcity value, I have to regard [it] as being more valuable than the Mona Lisa." But one can see what Edwards means. The Mona Lisa's smile suggests the depths of human personality, but it's one among many Renaissance portraits. The Antikythera Mechanism is one of a kind, and it has revolutionized our understanding of the ancient world.

What does the Mechanism do? Using both the Egyptian solar calendar— essentially the same as our own, with 365 days and a quadrennial leap day— and several longer, lunar-based cycles, it describes the orbits of the then-known solar system (the moon and five planets), together with their periodicities and eccentricities. On this basis it predicts eclipses. It integrates the stellar world as well by means of the Zodiac.

In short, a device about the size of a large dictionary volume, operated by means of a single, external hand crank, provides through its interlocking dials and gears a complete account of the heavens as they would be known until Galileo's time.

The only error in the system is that it is earth-centered (the Greek astronomer Aristarchus had proposed a heliocentric model of the universe about two centuries earlier, but the geocentric model prevailed). It's entirely accurate, however, from the standpoint of a human observer, which was exactly its purpose, and thus it represents a virtual compendium of ancient astronomy.

What's staggering is not only how much the ancients knew, but how compactly, elegantly and intricately they could display it.

Echoes of Rocky

The Mechanism and its replicas comprise the last and culminating feature of the exhibit, which ranges from warped elm planks from the sunken vessel itself to the larger-than-life statue of a youth, the so-called Antikythera Ephebe (c. 340 B.C.E.), which is one of the glories of the Museum's collection of ancient art. It's contemporaneous with the world-famous Hermes of Praxiteles in the Museum of Olympia, and for my money a superior work. It certainly does anchor a room.

Most of the other sculpture is small-scaled. One exception is an imposing Head of a Philosopher (identified with the Fourth-Century philosopher Antisthenes, but also possibly representing a certain magician, Bion the Borysthene). In an era when a kitschy statue of a contemporary movie star impersonating a punch-drunk boxer can grace the front of a famous Philadelphia art museum, we need not be over-scrupulous about such things. Unlike Rocky, it's a fine and expressive piece.

The dates of both the Head and the Ephebe make it clear that the doomed ship's cargo wasn't primarily commercial, but loot for the adornment of Rome. Beauty and larceny have always gone hand in hand, as the fate of another famous Philadelphia art collection has recently reminded us.

Speaking of Rocky, the doomed ship's trove includes a small but excellent figure of a Hellenistic boxer, as well as several other pieces that remind us how good the Greeks were at both figurines and oversize sculpture.

The King Tut exception

Even more refined miniaturization can be found on the coins also recovered from the wreck. The pottery is mostly unexceptional, but the display includes some fine platterware and some of the best glassware we have from antiquity.

How exceptional was the haul of our treasure ship? It's hard to say, but it would have been only one of many that brought back the spoil of the East. Most such ships presumably reached their destinations and dispersed their cargo.

Thanks to modern museums, we can better trace and identify loot these days (sometimes our museums seem to be disgorging as much of their ill-gotten art as adding to it). Temples and tombs would have been the comparable repositories of the ancient world; but over time, professional looters and barbarians have emptied their treasures.

King Tut's tomb was a notable exception. So was the ship the waves claimed off Antikythera.

Human carcasses

The first of the divers to reach the wreck a hundred years ago came back frantic with the news that he had seen the carcasses of men and horses on the sea floor. (Some of the first divers died of the effects of decompression, the ship's last victims.) But what that credulous original discoverer found brought back to life a vanished age and rewrote the history of human technology.

No one dives for sponges today, of course; they are manufactured synthetically. Had that technology been available in 1900, the Antikythera Mechanism might still be resting at the bottom of the Aegean Sea.