Ptolemy | |
---|---|
Born | c. 90 |
Died | c. 168 Alexandria, Egypt |
Occupation | Astronomer, astrologer, geographer, mathematician |
Claudius Ptolemaeus (Klaúdios Ptolemaîos; c. 90–168), known in English as Ptolemy, was an Egyptian astronomer, astrologer, geographer, mathematician, and poet.[1][2] He was born in the town of Ptolemais Hermiou in the Thebaid, Upper Egypt, and died in Alexandria, Egypt.[3]
Ptolemy was the author of several scientific treatises, at least three of which were of continuing importance to later Islamic and European science. The first is the astronomical treatise now known as the Almagest. The second is the Geography, which is a thorough discussion of the geographic knowledge of the ancient world. The third is the astrological treatise known as the Tetrabiblos, in which he attempted to adapt horoscopic astrology to Aristotelian natural philosophy.
Background[]
Few details of Ptolemy's life are known. Many scholars have concluded that ethnically, Ptolemy was likely an Egyptian, though Hellenized.[4][5][6][7] He is known to have utilised Babylonian astronomical data.[8][9] He was often known in later Arabic sources as "the Upper Egyptian",[10] suggesting that he may have had origins in southern Egypt.[7] Later Arabic astronomers, geographers and physicists referred to him by his name in Arabic: بطليموس Batlaymus.[11]
Origins[]

Fayum mummy portraits of Greco-Egyptians in the 1st century CE
Under Greco-Roman rule, Egypt hosted several Greek settlements, mostly concentrated in Alexandria, but also in a few other cities, where Greek settlers lived alongside some seven to ten million native Egyptians.[12] Faiyum's earliest Greek inhabitants were soldier-veterans and cleruchs (elite military officials) who were settled by the Ptolemaic kings on reclaimed lands.[13][14] Native Egyptians also came to settle in Faiyum from all over the country, notably the Nile Delta, Upper Egypt, Oxyrhynchus and Memphis, to undertake the labor involved in the land reclamation process, as attested by personal names, local cults and recovered papyri.[15] It is estimated that as much as 30 percent of the population of Faiyum was Greek during the Ptolemaic period, with the rest being native Egyptians.[16] By the Roman period, much of the "Greek" population of Faiyum was made-up of either Hellenized Egyptians or people of mixed Egyptian-Greek origins.[17] By the time of Roman emperor Caracalla in the 2nd century CE, the only way to differentiate Alexandria's "Greeks" from "genuine" ethnic Egyptians was "by their speech."[18]
While commonly believed to represent Greek settlers in Egypt,[19][20] the Faiyum mummy portraits instead reflect the complex synthesis of the predominant Egyptian culture and that of the elite Greek minority in the city.[16] According to Walker, the early Ptolemaic Greek colonists married local women and adopted Egyptian religious beliefs, and by Roman times, their descendants were viewed as Egyptians by the Roman rulers, despite their own self-perception of being Greek.[21] The dental morphology[22] of the Roman-period Faiyum mummies was also compared with that of earlier Egyptian populations, and was found to be "much more closely akin" to that of ancient Egyptians than to Greeks or other European populations.[23]
The mathematics historian Victor J. Katz has criticized the modern misconception portraying the ancient Hellenistic scholars of Egypt as ethnically Greek or European, writing:[4]
- "But what we really want to know is to what extent the Alexandrian mathematicians of the period from the first to the fifth centuries C.E. were Greek. Certainly, all of them wrote in Greek and were part of the Greek intellectual community of Alexandria. And most modern studies conclude that the Greek community coexisted [...] So should we assume that Ptolemy and Diophantus, Pappus and Hypatia were ethnically Greek, that their ancestors had come from Greece at some point in the past but had remained effectively isolated from the Egyptians? It is, of course, impossible to answer this question definitively. But research in papyri dating from the early centuries of the common era demonstrates that a significant amount of intermarriage took place between the Greek and Egyptian communities [...] And it is known that Greek marriage contracts increasingly came to resemble Egyptian ones. In addition, even from the founding of Alexandria, small numbers of Egyptians were admitted to the privaleged classes in the city to fulfill numerous civic roles. Of course, it was essential in such cases for the Egyptians to become "Hellenized," to adopt Greek habits and the Greek language. Given that the Alexandrian mathematicians mentioned here were active several hundred years after the founding of the city, it would seem at least equally possible that they were ethnically Egyptian as that they remained ethnically Greek. In any case, it is unreasonable to portray them with purely European features when no physical descriptions exist."
Astronomy[]
The Almagest is the only surviving comprehensive ancient treatise on astronomy. Babylonian astronomers had developed arithmetical techniques for calculating astronomical phenomena, while astronomers such as Hipparchus had produced geometric models for calculating celestial motions. Ptolemy claimed to have derived his geometrical models from selected astronomical observations by his predecessors spanning more than 800 years, though astronomers have for centuries suspected that his models' parameters were adopted independently of observations.[24] Ptolemy presented his astronomical models in convenient tables, which could be used to compute the future or past position of the planets.[25] The Almagest also contains a star catalogue, which is an appropriated version of a catalogue created by Hipparchus. Its list of forty-eight constellations is ancestral to the modern system of constellations, but unlike the modern system they did not cover the whole sky (only the sky Hipparchus could see). Through the Middle Ages it was spoken of as the authoritative text on astronomy, with its author becoming an almost mythical figure, called Ptolemy, King of Alexandria.[26] The Almagest was preserved, like much of ancient science, in Arabic manuscripts (hence its familiar name). Because of its reputation, it was widely sought and was translated twice into Latin in the 12th century, once in Sicily and again in Spain.[27] Ptolemy's model, like those of his predecessors, was geocentric and was almost universally accepted until the appearance of simpler heliocentric models during the scientific revolution.
His Planetary Hypotheses went beyond the mathematical model of the Almagest to present a physical realization of the universe as a set of nested spheres,[28] in which he used the epicycles of his planetary model to compute the dimensions of the universe. He estimated the Sun was at an average distance of 1210 Earth radii while the radius of the sphere of the fixed stars was 20,000 times the radius of the Earth.[29]
Ptolemy presented a useful tool for astronomical calculations in his Handy Tables, which tabulated all the data needed to compute the positions of the Sun, Moon and planets, the rising and setting of the stars, and eclipses of the Sun and Moon. Ptolemy's Handy Tables provided the model for later astronomical tables or zījes. In the Phaseis (Risings of the Fixed Stars) Ptolemy gave a parapegma, a star calendar or almanac based on the hands and disappearances of stars over the course of the solar year.
Geography[]
Ptolemy's other main work is his Geographia. This also is a compilation of what was known about the world's geography in the ancient Mediterranean during his time. He relied somewhat on the work of an earlier geographer, Marinos of Tyre, and on gazetteers of the Roman and ancient Persian Empire, but most of his sources beyond the perimeter of the Empire were unreliable.[citation needed]
The first part of the Geographia is a discussion of the data and of the methods he used. As with the model of the solar system in the Almagest, Ptolemy put all this information into a grand scheme. Following Marinos, he assigned coordinates to all the places and geographic features he knew, in a grid that spanned the globe. Latitude was measured from the equator, as it is today, but Ptolemy preferred in book 8 to express it as the length of the longest day rather than degrees of arc (the length of the midsummer day increases from 12h to 24h as one goes from the equator to the polar circle). In books 2 through 7, he used degrees and put the meridian of 0 longitude at the most western land he knew, the "Blessed Islands", probably the Cape Verde islands (not the Canary Islands, as long accepted) as suggested by the location of the six dots labelled the "FORTUNATA" islands near the left extreme of the blue sea of Ptolemy's map here reproduced.
A 15th century manuscript copy of the Ptolemy world map, reconstituted from Ptolemy's Geographia (circa 150), indicating the countries of "Serica" and "Sinae" (China) at the extreme east, beyond the island of "Taprobane" (Sri Lanka, oversized) and the "Aurea Chersonesus" (Malay Peninsula).
Ptolemy also devised and provided instructions on how to create maps both of the whole inhabited world (oikoumenè) and of the Roman provinces. In the second part of the Geographia he provided the necessary topographic lists, and captions for the maps. His oikoumenè spanned 180 degrees of longitude from the Blessed Islands in the Atlantic Ocean to the middle of China, and about 80 degrees of latitude from The Shetlands to anti-Meroe (east coast of Africa); Ptolemy was well aware that he knew about only a quarter of the globe, and an erroneous extension of China southward suggests his sources did not reach all the way to the Pacific Ocean.
The maps in surviving manuscripts of Ptolemy's Geographia, however, date only from about 1300, after the text was rediscovered by Maximus Planudes. It seems likely that the topographical tables in books 2-7 are cumulative texts - texts which were altered and added to as new knowledge became available in the centuries after Ptolemy (Bagrow 1945). This means that information contained in different parts of the Geography is likely to be of different date.
A printed map from the 15th century depicting Ptolemy's description of the Ecumene, (1482, Johannes Schnitzer, engraver).
Maps based on scientific principles had been made since the time of Eratosthenes (3rd century BC), but Ptolemy improved projections. It is known that a world map based on the Geographia was on display in Autun, France in late Roman times. In the 15th century Ptolemy's Geographia began to be printed with engraved maps; the earliest printed edition with engraved maps was produced in Bologna in 1477, followed quickly by a Roman edition in 1478 (Campbell, 1987). An edition printed at Ulm in 1482, including woodcut maps, was the first one printed north of the Alps. The maps look distorted as compared to modern maps, because Ptolemy's data were inaccurate. One reason is that Ptolemy estimated the size of the Earth as too small: while Eratosthenes found 700 stadia for a great circle degree on the globe, in the Geographia Ptolemy uses 500 stadia. It is highly probable that these were the same stadion since Ptolemy switched from the former scale to the latter, between the Syntaxis and the Geographia and severely readjusted longitude degrees accordingly. If they both used the Attic stadion of about 185 meters, then the older estimate is 1/6 too large, and Ptolemy's value is 1/6 too small, a difference explained as due to ancient scientists' use of simple methods of measuring the earth, which were corrupted either high or low by a factor of 5/6, due to air's bending of horizontal light rays by 1/6 of the Earth's curvature.
Because Ptolemy derived many of his key latitudes from crude longest day values, his latitudes are erroneous on average by roughly a degree (2 degrees for Byzantium, 4 degrees for Carthage), though capable ancient astronomers knew their latitudes to more like a minute. (Ptolemy's own latitude was in error by 14'.) He agreed (Geographia 1.4) that longitude was best determined by simultaneous observation of lunar eclipses, yet he was so out of touch with the scientists of his day that he knew of no such data more recent than 500 years ago (Arbela eclipse). When switching from 700 stadia per degree to 500, he (or Marinos) expanded longitude differences between cities accordingly (a point 1st realized by P.Gosselin in 1790), resulting in serious over-stretching of the Earth's east-west scale in degrees, though not distance. Achieving highly precise longitude remained a problem in geography until the invention of the marine chronometer at the end of the 18th century. It must be added that his original topographic list cannot be reconstructed: the long tables with numbers were transmitted to posterity through copies containing many scribal errors, and people have always been adding or improving the topographic data: this is a testimony to the persistent popularity of this influential work in the history of cartography.
Astrology[]
Ptolemy's treatise on astrology, known as Tetrabiblios ("Four Books"), was the most popular astrological work of antiquity and also had great influence in the Islamic world and the medieval Latin West. It was first translated from Arabic into Latin by Plato of Tivoli (Tiburtinus), while he was in Spain (FA Robbins, 1940; Thorndike 1923). The Tetrabiblos is an extensive and continually reprinted treatise on the ancient principles of horoscopic astrology in four books (tetra means "four", biblos is "book"). That it did not quite attain the unrivaled status of the Almagest was perhaps because it did not cover some popular areas of the subject, particularly electional astrology (interpreting astrological charts for a particular moment to determine the outcome of a course of action to be initiated at that time), and medical astrology, which were later adoptions.
The great popularity that the Tetrabiblos did possess might be attributed to its nature as an exposition of the art of astrology and as a compendium of astrological lore, rather than as a manual. It speaks in general terms, avoiding illustrations and details of practice. Ptolemy was concerned to defend astrology by defining its limits, compiling astronomical data that he believed was reliable and dismissing practices (such as considering the numerological significance of names) that he believed to be without sound basis.
Much of the content of the Tetrabiblos was collected from earlier sources; Ptolemy's achievement was to order his material in a systematic way, showing how the subject could, in his view, be rationalized. It is, indeed, presented as the second part of the study of astronomy of which the Almagest was the first, concerned with the influences of the celestial bodies in the sublunar sphere. Thus explanations of a sort are provided for the astrological effects of the planets, based upon their combined effects of heating, cooling, moistening, and drying.
Ptolemy's astrological outlook was quite practical: he thought that astrology was like medicine, that is conjectural, because of the many variable factors to be taken into account: the race, country, and upbringing of a person affects an individual's personality as much if not more than the positions of the Sun, Moon, and planets at the precise moment of their birth, so Ptolemy saw astrology as something to be used in life but in no way relied on entirely.
Music[]
Ptolemy also wrote an influential work, Harmonics, on music theory and the mathematics of music. After criticizing the approaches of his predecessors, Ptolemy argued for basing musical intervals on mathematical ratios (in contrast to the followers of Aristoxenus and in agreement with the followers of Pythagoras) backed up by empirical observation (in contrast to the overly theoretical approach of the Pythagoreans). Ptolemy wrote about how musical notes could be translated into mathematical equations and vice versa in Harmonics. This is called Pythagorean tuning because it was first discovered by Pythagoras. However, Pythagoras believed that the mathematics of music should be based on the specific ratio of 3:2 whereas Ptolemy merely believed that it should just generally involve tetrachords and octaves. He presented his own divisions of the tetrachord and the octave, which he derived with the help of a monochord. Ptolemy's astronomical interests also appeared in a discussion of the "music of the spheres."
Optics[]
His Optics is a work that survives only in a poor Arabic translation and in about twenty manuscripts of a Latin version of the Arabic, which was translated by Eugene of Palermo (circa 1154). In it Ptolemy writes about properties of light, including reflection, refraction, and colour. The work is a significant part of the early history of optics.[30]
Named after Ptolemy[]
There are several characters or items named after Ptolemy, including:
- The crater Ptolemaeus on the Moon;
- The crater Ptolemaeus[31] on Mars;
- the asteroid 4001 Ptolemaeus;
- a character in the fantasy series The Bartimaeus Trilogy: this fictional Ptolemy is a young magician (from Alexandria) whom Bartimaeus loved; he made the journey into "the Other Place" being hunted by his cousin, because he was a magician;
- the name of Celestial Being's carrier ship in the anime Mobile Suit Gundam 00.
- track number 10 on Selected Ambient Works 85–92 by Aphex Twin.
- the Ptolemy Stone used in the mathematics courses at both St. John's College campuses.
See also[]
- Pei Xiu
- Ptolemy's Canon - a dated list of kings used by ancient astronomers.
- Ptolemy Cluster - star cluster described by Ptolemaeus.
- Ptolemy's theorem - mathematical theorem described by Ptolemaeus.
- Ptolemy's world map - map of the ancient world as described by Ptolemaeus.
- Zhang Heng
Footnotes[]
- ↑ Select Epigrams from the Greek Anthology By John William Mackail Page 246 ISBN 1406922943 2007
- ↑ Mortal am I, the creature of a day..
- ↑ Jean Claude Pecker (2001), Understanding the Heavens: Thirty Centuries of Astronomical Ideas from Ancient Thinking to Modern Cosmology, p. 311, Springer, ISBN 3540631984.
- ↑ 4.0 4.1 Victor J. Katz (1998). A History of Mathematics: An Introduction, p. 184. Addison Wesley, ISBN 0-321-01618-1
- ↑ George Sarton (1936). "The Unity and Diversity of the Mediterranean World", Osiris 2, p. 406-463 [429].
- ↑ John Horace Parry (1981). The Age of Reconnaissance, p. 10. University of California Press. ISBN 0520042352.
- ↑ 7.0 7.1 Martin Bernal (1992). "Animadversions on the Origins of Western Science", Isis 83 (4), p. 596-607 [602, 606].
- ↑ Asger Aaboe, Episodes from the Early History of Astronomy, New York: Springer, 2001), p. 62-65.
- ↑ Alexander Jones, "The Adaptation of Babylonian Methods in Greek Numerical Astronomy," in The Scientific Enterprise in Antiquity and the Middle Ages, p. 99.
- ↑ J. F. Weidler (1741). Historia astronomiae, p. 177. Wittenberg: Gottlieb. (cf. Martin Bernal (1992). "Animadversions on the Origins of Western Science", Isis 83 (4), p. 596-607 [606].)
- ↑ edited by Shahid Rahman, Tony Street, Hassan Tahiri. (2008). "The Birth of Scientific Controversies, The Dynamics of the Arabic Tradition and Its Impact on the Development of Science: Ibn al-Haytham’s Challenge of Ptolemy’s Almagest". The Unity of Science in the Arabic Tradition. 11. Springer Netherlandsdoi=10.1007/978-1-4020-8405-8. pp. 183–225 [183]. doi:10.1007/978-1-4020-8405-8. ISBN 978-1-4020-8404-1.
- ↑ Adams, Winthrope L in Bugh, Glenn Richard. ed. "The Hellenistic Kingdoms". The Cambridge Companion to the Hellenistic World. Cambridge: Cambridge University Press. 2006, p. 39
- ↑ Stanwick, Paul Edmund. Portraits of the Ptolemies: Greek Kings as Egyptian Pharaohs. Austin: University of Texas Press. 2003, p. 23
- ↑ Adams, op cit.
- ↑ Bagnall, R.S. in Susan Walker, ed. Ancient Faces : Mummy Portraits in Roman Egypt (Metropolitan Museum of Art Publications). New York: Routledge, 2000, p. 27
- ↑ 16.0 16.1 Bagnall, op cit.
- ↑ Bagnall, pp. 28-29
- ↑ qtd. in Alan K. Bowman, Egypt after the Pharaohs, 332 BC − AD 642, Berkeley: University of California Press, 1996, p. 126: "genuine Egyptians can easily be recognized among the linen-weavers by their speech."
- ↑ Egyptology Online: Fayoum mummy portraits accessed on January 16, 2007
- ↑ Encyclopædia Britannica Online - Egyptian art and architecture - Greco-Roman Egypt accessed on January 16, 2007
- ↑ Walker, Susan, op cit., p. 24
- ↑ Dentition helps archaeologists to assess biological and ethnic population traits and relationships
- ↑ Irish JD (2006). "Who were the ancient Egyptians? Dental affinities among Neolithic through postdynastic peoples.". Am J Phys Anthropol 129 (4): 529-43
- ↑ "Dennis Rawlins". The International Journal of Scientific History. Retrieved 2009-10-07.
{{cite web}}
: - ↑ Bernard R. Goldstein, "Saving the Phenomena: The Background to Ptolemy's Planetary Theory", Journal for the History of Astronomy, 28 (1997): 1-12
- ↑ S. C. McCluskey, Astronomies and Cultures in Early Medieval Europe, Cambridge: Cambridge Univ. Pr. 1998, pp. 20-21.
- ↑ Charles Homer Haskins, Studies in the History of Mediaeval Science, New York: Frederick Ungar Publishing, 1967, reprint of the Cambridge, Mass., 1927 edition
- ↑ Dennis Duke, Ptolemy's Cosmology
- ↑ Bernard R. Goldstein, ed., The Arabic Version of Ptolemy's Planetary Hypotheses, Transactions of the American Philosophical Society, 57, 4 (1967), pp. 9-12.
- ↑ Smith, A. Mark (1996). Ptolemy's Theory of Visual Perception– An English translation of the Optics. The American Philosophical Society. ISBN 0-87169-862-5. http://books.google.com/books?id=mhLVHR5QAQkC&pg=PP1&dq=ptolemy+theory+of+visual+perception. Retrieved 27 June 2009.
- ↑ Mars Labs. Google Maps.
References[]
Texts and translations[]
- Bagrow, L. (January 1, 1945). "The Origin of Ptolemy's Geographia". Geografiska Annaler 27: 318–387. doi:10.2307/520071. ISSN 16513215.
- Berggren, J. Lennart, and Alexander Jones. 2000. Ptolemy's Geography: An Annotated Translation of the Theoretical Chapters. Princeton and Oxford: Princeton University Press. ISBN 0-691-01042-0.
- Campbell, T. (1987). The Earliest Printed Maps. British Museum Press.
- Hübner, Wolfgang, ed. 1998. Claudius Ptolemaeus, Opera quae exstant omnia Vol III/Fasc 1: ΑΠΟΤΕΛΕΣΜΑΤΙΚΑ (= Tetrabiblos). De Gruyter. ISBN 978-3-598-71746-8 (Bibliotheca scriptorum Graecorum et Romanorum Teubneriana). (The most recent edition of the Greek text of Ptolemy's astrological work, based on earlier editions by F. Boll and E. Boer.)
- Neugebauer, Otto (1975). A History of Ancient Mathematical Astronomy. I-III. Berlin and New York: Sprnger Verlag.
- Nobbe, C. F. A., ed. 1843. Claudii Ptolemaei Geographia. 3 vols. Leipzig: Carolus Tauchnitus. (The most recent edition of the complete Greek text)
- Ptolemy. 1930. Die Harmonielehre des Klaudios Ptolemaios, edited by Ingemar Düring. Göteborgs högskolas årsskrift 36, 1930:1. Göteborg: Elanders boktr. aktiebolag. Reprint, New York: Garland Publishing, 1980.
- Ptolemy. 2000. Harmonics, translated and commentary by Jon Solomon. Mnemosyne, Bibliotheca Classica Batava, Supplementum, 0169-8958, 203. Leiden and Boston: Brill Publishers. ISBN 9004115919
- Stevenson, Edward Luther (trans. and ed.). 1932. Claudius Ptolemy: The Geography. New York: New York Public Library. Reprint, New York: Dover, 1991. (This is the only complete English translation of Ptolemy's most famous work. Unfortunately, it is marred by numerous mistakes and the placenames are given in Latinised forms, rather than in the original Greek).
- Stückelberger, Alfred, and Gerd Graßhoff (eds). 2006. Ptolemaios, Handbuch der Geographie, Griechisch-Deutsch. 2 vols. Basel: Schwabe Verlag. ISBN 978-3-7965-2148-5. (Massive 1018 pp. scholarly edition by a team of a dozen scholars that takes account of all known manuscripts, with facing Greek and German text, footnotes on manuscript variations, color maps, and a CD with the geographical data)
- Taub, Liba Chia (1993). Ptolemy's Universe: The Natural Philosophical and Ethical Foundations of Ptolemy's Astronomy. Chicago: Open Court Press. ISBN 0-8126-9229-2.
External links[]
Primary sources[]
- Ptolemy's Tetrabiblos at LacusCurtius (English translation of a portion of the material, with introductory material)
- Entire Tetrabiblos of J.M. Ashmand's 1822 translation.
- Ptolemy's Geography at LacusCurtius (English translation, incomplete)
- Extracts of Ptolemy on the country of the Seres (China) (English translation)
- Geographia (the Balkan Provinces, with old maps) at Sorin Olteanu's LTDM Project (soltdm.com)
- Almagest books 1- 13 The complete text of Heiberg's edition (PDF).
- Almagest books 1-6 @ archive.org
Secondary material[]
- Arnett, Bill (2008). "Ptolemy, the Man". obs.nineplanets.org. Retrieved 2008-11-24.
{{cite web}}
: - Danzer, Gerald (1988). "Cartographic Images of the World on the Eve of the Discoveries". The Newberry Library. Retrieved 26 November 2008.
{{cite web}}
: - Fiks, Norbert (1997–2002). "10. Der Nordwesten bei Ptolemaeus". Die Römer in Ostfriesland . www.fiks.de. Retrieved 26 November 2008.
{{cite web}}
: CS1 maint: date format (link) - Haselein, Frank (2007). "Κλαυδιου Πτολεμιου: Γεωγραφικῆς Ύφηγήσεως" . Frank Haselein. Retrieved 2008-11-24.
{{cite web}}
: CS1 maint: unrecognized language (link) - Houlding, Deborah (2003). "The Life & Work of Ptolemy". Skyscript.co. Retrieved 2008-11-24.
{{cite web}}
: - Sprague, Ben (2001–2007). "Claudius Ptolemaeus (Ptolemy): Representation, Understanding, and Mathematical Labeling of the Spherical Earth". Center for Spatially Integrated Social Science. Retrieved 26 November 2008.
{{cite web}}
: CS1 maint: date format (link)
Animated Illustrations[]
- Java simulation of the Ptolemaic System - at Paul Stoddard's Animated Virtual Planetarium, Northern Illinois University
- Animation of Ptolemy's Two Solar Hypotheses
- Epicycle and Deferent Demo - at Rosemary Kennett's website at the University of Syracuse
- Flash animation of Ptolemy's universe. (best in Internet Explorer)