|
|
A Source Book in Greek Science
Contents:
Show Summary
Hide Summary
General SummaryIn the history of science both ancient and modern there is often considerable question of priority of discovery. This is to be expected in view of the interchange of ideas among men of science and the cumulative nature of science, since advances are made from a body of knowledge that has become common property. Certain Pythagoreans had, as we have seen, abandoned the view of the earth as central and immovable and had made the earth and all the heavenly bodies revolve about the central fire. Now the explanation of the apparent diurnal revolution of the heavens by the hypothesis of the earth at the center rotating on its axis is different from the earlier Pythagorean view. But it may represent a development of that view by the transference of the central fire to the center of the earth. In any case it had enough in common with the earlier system to cause some confusion in the later tradition. And so we find priority in the theory of the earth’s axial rotation accorded in some sources to Philolaus, Hicetas, Ecphantus, and Plato, as well as to Heraclides of Pontus. Apart from the question of priority, the evidence seems to indicate that Heraclides adopted the hypothesis that the earth (whether or not at the center of the universe) rotated daily on its axis.On the planetary theory of Heraclides the evidence is scanty and the interpretations conflicting. Some have held that he explained the variations in the brightness of Venus and Mercury by supposing that these planets revolved around the sun. On the other hand, a recent study of B. L. Van der Waerden ascribes to Heraclides the view that the earth, the sun, and the planets revolve around a common center, a view much like that of the earlier Pythagoreans. The view of Schiaparelli that Heraclides anticipated Aristarchus in holding that the earth revolved around the sun is refuted by Heath (Aristarchus of Samos, pp. 260–275). It is also very doubtful that Heraclides put forward the theory that the superioras well as the inferior planets revolved around the sun, a theory which, together with the notion of the sun’s revolution around the earth, would foreshadow the Tychonic system.One other point may be noted. A system in which Mercury and Venus revolve about the sun, and the sun about the earth, a system which some have ascribed to Heraclides, would in effect involve epicyclic motion which played so important a role in the ultimate development of Greek astronomy; for in describing circular orbits about the sun as the sun describes a circular orbit about the earth, Venus and Mercury would trace epicyclic paths.
ASTRONOMY
The Rotation of the Earth on Its Axis
Cicero, Academica II. 39.123
Hicetas1 of Syracuse, as Theophrastus tells us, holds that the heavens, sun, moon, and stars, all the heavenly bodies, in short, are at rest, and that nothing in the universe moves except the earth,2 and as the earth turns and rotates about its axis at very high speed the effect is exactly the same as if the heavens were rotating and the earth at rest. And there are some who think that this is what Plato is saying in the Timaeus, but somewhat more obscurely.3
Hippolytus, Refutation of All Heresies I. 15
Ecphantus a Syracusan said . . . that the earth, the center of the universe, moved about its own center toward the east.
Diogenes Laertius VIII. 85
Philolaus was the first to hold that the earth rotates in a circle, though others say it was Hicetas of Syracuse.
Simplicius, Commentary on Aristotle’s De Caelo, pp. 444.33–445.3(Heiberg)
There have been some, among them Heraclides of Pontus4 and Aristarchus, who thought that the phenomena could be accounted for by supposing the heaven and stars to be at rest, and the earth to be in motion about the poles of the equator from west [to east], making approximately one complete rotation each day. The word "approximately" is added because of the motion of the sun amounting to one degree.1
1 The tradition with respect to the Pythagorean philosophers Hicetas and Ecphantus is obscure and has been variously interpreted. The agreement between their views and those of Heraclides of Pontus led P. Tannery to the hypothesis that the tradition arose from Hera-elides’ having expounded his views through the medium of dialogues in which Hicetas and Ecphantus appeared as characters.
2 Perhaps Cicero is speaking merely of diurnal motion, for the system described would by no means fit the observed planetary, solar, and lunar motions.
3 "And the earth, our foster mother, revolved [figure table] about the axis that extends through the universe he contrived as the guardian and creator of night and day." The difficulty is with the interpretation of
(or
, a difficulty of which the ancients themselves were aware, as this passage of Cicero and passages of the commentators on Aristotle, De Caelo II. 13 (see p. 96, above) indicate.
4 Heraclides of Pontus (ca. 388- ca. 310 B.C.) probably was a pupil of Plato and perhaps, too, of Aristotle. His literary work covered many fields, including ethics, physics, astronomy, music, literary criticism, and rhetoric.
1 I.e., the sun’s motion along the ecliptic, the whole circle being completed in one year and the daily motion therefore amounting to about 1° Cf. also Aìtius III. 13.3: "Heraclides of Pontus and Ecphantus the Pythagorean suppose that the earth moves, not however with complete change in position
, but by rotating
from west to east about its own center, fixed upon its axis like a wheel."
Simplicius, op. cit., p. 519.9–11: "By assuming that the earth was at the center and rotated while the heaven was at rest Heraclides of Pontus thought he ’saved the phenomena.’"
Contents:
Chicago:
Marcus Tullius Cicero, "The Rotation of the Earth on Its Axis," A Source Book in Greek Science, ed. Heiberg in A Source Book in Greek Science, ed. Morris R. Cohen and I. E. Drabkin (Cambridge: Harvard University Press, 1948), 105–107. Original Sources, accessed June 7, 2026, http://www.originalsources.com/Document.aspx?DocID=HYHP69TXR6DTUVZ.
MLA:
Cicero, Marcus Tullius. "The Rotation of the Earth on Its Axis." A Source Book in Greek Science, edited by Heiberg, Vol. VIII., in A Source Book in Greek Science, edited by Morris R. Cohen and I. E. Drabkin, Cambridge, Harvard University Press, 1948, pp. 105–107. Original Sources. 7 Jun. 2026. http://www.originalsources.com/Document.aspx?DocID=HYHP69TXR6DTUVZ.
Harvard:
Cicero, MT, 'The Rotation of the Earth on Its Axis' in A Source Book in Greek Science, ed. . cited in 1948, A Source Book in Greek Science, ed. , Harvard University Press, Cambridge, pp.105–107. Original Sources, retrieved 7 June 2026, from http://www.originalsources.com/Document.aspx?DocID=HYHP69TXR6DTUVZ.
|