Born: 387 BC in Heraclea Pontica (now Eregli, Turkey)
Died: 312 BC in Heraclea Pontica

Heraclides of Pontus has achieved fame for a long time as the first to propose that the sun was the centre of the solar system but this has been shown to be due to a misinterpretation of what he wrote.

We do have some details of Heraclides' life. His father was named Euthyphron, a wealthy man of high status from Heraclea Pontica, who was descended from one of the original founders of this Greek city on the south coast of the Black Sea. Heraclides attended the Academy in Athens and was left in charge of it during Plato's third visit to Sicily in 360 BC.

Although in some sense he was a pupil of Plato, he also studied with Aristotle and with Speusippus who was Plato's successor as head of the Academy. When Speusippus died in 339 BC there was an election for the new leader despite Xenocrates having been chosen to head the Academy by Speusippus. It was a close battle between Xenocrates, Menedemus of Pyrrha and Heraclides Ponticus but Xenocrates triumphed by just a few votes.

At this point Heraclides left the Athens and returned to Heraclea Pontica. Stories told of his death are not really believable yet they must at least point to the type of person that Heraclides was. It is said that Heraclea Pontica suffered a famine and Heraclides bribed the messengers sent to the Delphic oracle to say that the city would be saved if Heraclides was given a gold crown and made a hero after his death. The story relates that Heraclides died while being presented with the golden crown.

Perhaps Heraclides had the last laugh here for indeed he did become a hero after is death based on a false interpretation of his writing. For example Heath [2] writes:-

Heraclides of Pontus, Plato's famous pupil, is known on clear evidence to have discovered that Venus and Mercury revolve round the sun like satellites. He may have come to the same conclusion about the superior planets but this is not certain...

The misunderstanding comes from a commentary by Calcidius in the fifth century AD on Plato's Timaeus. This reads (in Neugebauer's translation in [3]):-

Heraclides Ponticus, when describing the circle of Venus as well as that of the sun, and giving the two circles one centre and one mean motion, showed how Venus is sometimes above, sometimes below the sun.

T H Martin, in 1849, pointed out the significance of the passage saying that Venus is sometimes above, sometimes below the sun clearly means that Heraclides believed that it was in orbit round the sun. Schiaparelli accepted Martin's argument and went further to claim that Heraclides must have proposed the theory that the sun revolves round the earth, but the planets revolve round the sun. This theory, first proposed by Tycho Brahe at the end of the 16^th century, was never as far as we know put forward by a Greek astronomer.

Neugebauer [3] shows clearly that the passage indicating that Venus is sometimes above, sometimes below the sun, means that it is sometimes ahead of the sun, sometimes behind it. Toomer in [1] agrees completely with Neugebauer's interpretation but a still more amazing interpretation of Heraclides had been proposed by van der Waerden. Rather than basing his argument on Calcidius's words, van der Waerden interpreted a diagram in Calcidius to mean that the sun, Venus and the earth all revolve round a common centre.

The article [6] by van der Waerden was an attempt by him to defend his hypothesis despite the new interpretation of the situation by Neugebauer. It is an unconvincing article and it seems to only repeat van der Waerden's earlier hypothesis without making any attempt to counter the rather simple and totally convincing argument by Neugebauer.

Heraclides does, however, still have a claim to fame for an astronomical hypothesis. A number of sources quote his belief that the earth is at the centre of the universe but that it rotates on its axis once a day. Certainly he is the first known to have held this view and deserves great credit for it.

We do know a little more concerning Heraclides. He is said to have (see [1]):-

... dressed richly, was very fat and stately, and was nicknamed "stately and magnificent" by the Athenians.

This nickname is a Greek pun based on the word Pompikos (meaning stately and magnificent) replacing Pontikos (meaning from Pontus).

1.T L Heath, A history of Greek mathematics I, II (Oxford, 1931).

2.O Neugebauer, A history of ancient mathematical astronomy (New York, 1975).

Articles:

1. E Craig (ed.), Routledge Encyclopedia of Philosophy 4 (London-New York, 1998), 363-364.
2. B S Eastwood, Heraclides and heliocentrism : texts, diagrams, and interpretations, J. Hist. Astronom. 23 (4) (1992), 233-260.
3. B L van der Waerden, On the motion of the planets according to Heraclides of Pontus, Arch. Internat. Hist. Sci. 28 (103) (1978), 167-182.
4. F Wehrli, Herakleides Pontikos, in Die Schule des Aristoteles, Texte und Kommentar VII (Basel, 1969).

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