6th Century BC
THALES OF MILETUS
“I will be sufficiently rewarded if when telling it to others you will not claim the discovery as your own, but will say it was mine.”
Thales of Miletus is a Greek philosopher, born in Miletus, Asia Minor and existed between 635?-546? BC.
He was the founder of Greek philosophy, and was considered one of the Seven Wise Men of Greece. Thales became famed for his knowledge of astronomy after predicting the eclipse of the sun that occurred on May 28, 585 bc. He is also said to have introduced geometry in Greece. According to Thales, the original principle of all things is water, from which everything proceeds and into which everything is again resolved. Before Thales, explanations of the universe were mythological, and his concentration on the basic physical substance of the world marks the birth of scientific thought. Thales left no writings; knowledge of him is derived from an account in Aristotle's Metaphysics.
SOURCE:
Thales." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
PYTHAGORAS
Pythagoras was born on the island of Sámos and existed between 582?-496BC.
Pythagoras is said to have been driven from Sámos by his disgust for the tyranny of Polycrates. About 530 bc Pythagoras settled in Crotona, a Greek colony in southern Italy, where he founded a movement with religious, political, and philosophical aims, known as Pythagoreanism.
The Pythagoreans adhered to certain mysteries, similar in many respects to the Orphic mysteries. Obedience and silence, abstinence from food, simplicity in dress and possessions, and the habit of frequent self-examination were prescribed. The Pythagoreans believed in immortality and in the transmigration of souls. Pythagoras himself was said to have claimed that he had been Euphorbus, a warrior in the Trojan War, and that he had been permitted to bring into his earthly life the memory of all his previous existences.
Among the extensive mathematical investigations carried on by the Pythagoreans were their studies of odd and even numbers and of prime and square numbers. From this arithmetical standpoint they cultivated the concept of number, which became for them the ultimate principle of all proportion, order, and harmony in the universe. Through such studies they established a scientific foundation for mathematics. In geometry the great discovery of the school was the hypotenuse theorem, or Pythagorean theorem, which states that the square of the hypotenuse of a right triangle is equal to the sum of the squares of the other two sides.
The astronomy of the Pythagoreans marked an important advance in ancient scientific thought, for they were the first to consider the earth as a globe revolving with the other planets around a central fire. They explained the harmonious arrangement of things as that of bodies in a single, all-inclusive sphere of reality, moving according to a numerical scheme. Because the Pythagoreans thought that the heavenly bodies are separated from one another by intervals corresponding to the harmonic lengths of strings, they held that the movement of the spheres gives rise to a musical sound—the “harmony of the spheres.”
SOURCE:
"Pythagoras." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
5th Century BC
ANXAGORAS
“In everything there is a portion of everything except Mind. “
Anaxogars was born in Clazomenae (near modern İzmir, Turkey) and existed between 500?-428 BC. Anaxagoras was the first philosopher to settle (circa 480) in Athens. Anaxagoras had taught in Athens for about 30 years when he was imprisoned for impiety for suggesting that the sun is a hot stone and the moon made of earth. Later he went to Ionia (in Asia Minor) and settled at Lampsacus, a colony of Miletus, where he died.
He is the Greek philosopher who introduced the notion of nous (Greek, “mind” or “reason”) into the philosophy of origins Anaxagoras explained his philosophy in Peri Physeos (On Nature), but only fragments of the books have survived. He held that all matter had existed originally as atoms, or molecules; that these atoms, infinitely numerous and infinitesimally small, had existed from all eternity; and that order was first produced out of this infinite chaos of minute atoms through the influence and operation of an eternal intelligence (nous). He also believed that all bodies are simply aggregations of atoms, for example, that a bar of gold, iron, or copper is composed of inconceivably minute particles of the same material.
SOURCE:
"Anaxagoras." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
ZENO OF ELEA
Zeno of Elea flourished at the 5th century bc and was born in Elea, in southwestern Italy. He became a favorite disciple of the Greek philosopher Parmenides and accompanied him to Athens at the age of about 40. He is a Greek mathematician and the philosopher of the Eleatic school, known for his philosophical paradoxes. In Athens, Zeno taught philosophy for some years, concentrating on the Eleatic system of metaphysics. The Athenian statesmen Pericles and Callias (flourished 5th century bc) studied under him. Zeno later returned to Elea and, according to traditional accounts, joined a conspiracy to rid his native town of the tyrant Nearchus; the conspiracy failed and Zeno was severely tortured, but he refused to betray his accomplices. Further circumstances of his life are not known.
Philosophically, Zeno accepted Parmenides' belief that the universe, or being, is a single, undifferentiated substance, a oneness, although it may appear diversified to the senses. Zeno's intention was to discredit the senses, which he sought to do through a brilliant series of arguments, or paradoxes, on time and space that have remained complex intellectual puzzles to this day. A typical paradox asserts that a runner cannot reach a goal because, in order to do so, he must traverse a distance; but he cannot traverse that distance without first traversing half of it, and so on, ad infinitum. Because an infinite number of bisections exist in a spatial distance, one cannot travel any distance in finite time, however short the distance or great the speed. This argument, like several others of Zeno, is intended to demonstrate the logical impossibility of motion. In that the senses lead us to believe in the existence of motion, the senses are illusory and therefore no obstacle to accepting the otherwise implausible theories of Parmenides. Zeno is noted not only for his paradoxes, but for inventing the type of philosophical argument they exemplify. Thus Aristotle named him the inventor of dialectical reasoning.
SOURCE:
"Zeno of Elea." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
DEMOCRITUS
“In reality we apprehend nothing for certain, but only as it changes according to the condition of our body, and of the things that impinge or offer resistance to it.” Democritus was born in Abdera, Thrace and existed between 460?-370? BC.
He developed the atomic theory of the universe, which had been originated by his mentor, the philosopher Leucippus. According to his exposition of the atomic theory of matter, all things are composed of minute, invisible, indestructible particles of pure matter (atoma,”indivisibles”), which move about eternally in infinite empty space (kenon,”the void”). Although atoms are made up of precisely the same matter, they differ in shape, size, weight, sequence, and position. Qualitative differences in what the senses perceive and the birth, decay, and disappearance of things are the results not of characteristics inherent in atoms but of quantitative arrangements of atoms. Democritus viewed the creation of worlds as the natural consequence of the ceaseless whirling motion of atoms in space. Atoms collide and spin, forming larger aggregations of matter.
Democritus also wrote on ethics, proposing happiness, or “cheerfulness,” as the highest good—a condition to be achieved through moderation, tranquillity, and freedom from fear. In later histories, Democritus was known as the Laughing Philosopher, in contrast to the more somber and pessimistic Heraclitus, the Weeping Philosopher. His atomic theory anticipated the modern principles of the conservation of energy and the irreducibility of matter.
SOURCE:
Brumbaugh, Robert S. "Democritus." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
EUDOXUS
Eudoxus was born in Cnidus (in what is now Turkey) and existed between 408-355BC.
He is a Greek astronomer and mathematician, who made important contributions to the field of geometry and who proposed the first systematic explanation for the motions of the sun, moon, and planets
Additionally, Eudoxus founded a school at Cyzicus. He is often credited with the discovery that the solar year is about 6 hours longer than 365 days. Eudoxus also attempted to explain the motions of the sun, moon, and planets through a model of the solar system based on a complicated arrangement of rotating spheres. His model was moderately successful in predicting these motions. Eudoxus also made important discoveries in mathematics. It is believed that he discovered much of the geometry later included in Elements, the comprehensive treatise on mathematics written by the Greek mathematician Euclid.
SOURCE:
"Eudoxus (of Cnidus)." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
4th Century BC
HERACLIDES
Heraclides Ponticus, existed between c. 390 BC – c. 310 BC, was a Greek philosopher and astronomer who lived and died at Heraclea Pontica, now Karadeniz Ereğli, Turkey. He is best remembered for proposing that the earth rotates on its axis, from west to east, once every 24 hours. He is also frequently hailed as the originator of the heliocentric theory, although this is doubted.
Heraclides proposed that the apparent daily motion of the stars was created by the rotation of the Earth on its axis once a day. This view contradicted the accepted Aristotelian model of the universe, which said that the earth was fixed and that the stars and planets in their respective spheres might also be fixed. Simplicius says that Heraclides proposed that the irregular movements of the planets can be explained if the earth moves while the sun stays still.
Although some historians have proposed that Heraclides taught that Venus and Mercury revolve around the Sun, a detailed investigation of the sources has shown that "nowhere in the ancient literature mentioning Heraclides of Pontus is there a clear reference for his support for any kind of heliocentrical planetary position."
A punning on his name, dubbing him Heraclides "Pompicus," suggests he may have been a rather vain and pompous man and the target of much ridicule. According to Diogenes Laertius, he forged plays under the name of Thespis, and according to the same author, this time drawing from a different source, Dionysius the Deserter composed plays and forged them under the name of Sophocles. Heraclides was deceived by this easily and cited from them as the words of Aeschylus and Sophocles.However, Heraclides seems to have been a versatile and prolific writer on philosophy,mathematics, music, grammar, physics, history and rhetoric, notwithstanding doubts about attribution of many of the works. It appears that he composed various works in dialogue form.
Heraclides also seems to have had an interest in the occult. In particular he focused on explaining trances, visions and prophecies in terms of the retribution of the gods, and reincarnation.
SOURCE:
“Heraclides Ponticus.” http://en.wikipedia.org/wiki/Heraclides_Ponticus. 20 October 2011 .
3rd Century BC
ZENO OF CITIUM
“"We have two ears and one mouth, so we should listen more than we say."
Zeno of Citium flourished late 4th and early 3rd century bc and was born in Citium, Cyprus. He is the Greek philosopher who founded the school of philosophy, known as Stoicism at about 300BC. The name of the school was derived from Stoa Poikilē (“painted porch”), the name given to the public portico where the master taught his disciples. Moral obligation, self-control, and living in harmony with nature were some of the principles of practical ethics with which Zeno was chiefly concerned. He taught in Athens for more than 50 years and was publicly honored for his upright manner of living. It is said, however, that he refused the offer of Athenian citizenship out of loyalty to his native Cyprus. Zeno left no written accounts of his teachings, but they were transmitted by his many disciples.
SOURCE:
"Zeno of Citium." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
HEROPHILUS
Herophilus is an Alexandrian physician, born in Chalcedon (now Kadiköy, Turkey) and existed between circa 335-280BC.
He known as the father of scientific anatomy because he was the first to base his conclusions on dissection of the human body. He studied the brain, recognizing it as the center of the nervous system. He distinguished the motor from the sensory nerves and accurately described the eye, brain, liver, and pancreas and the salivary and genital organs. He was first to recognize that the arteries contain blood, not air. His works, which include commentaries on Hippocrates and a treatise on anatomy, were lost.
SOURCE:
“Herophilus." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
ARISTARCHUS
Aristarchus from the island of Samos, in south eastern Greece at the Aegean Sea, existed between 310?-250? BC.
He is a Greek astronomer who was the first to assert that the earth revolves around the sun. His belief that the earth revolves around the sun is known only through the writings of Greek mathematician and inventor Archimedes; none of the works written by Aristarchus on the subject have survived. In his only surviving work, On the Dimensions and Distances of the Sun and Moon, Aristarchus described a method for estimating the relative distances of the sun and moon from the earth. Although his method was essentially correct, his estimates were wrong because of his inadequate knowledge of mathematics and his lack of accurate instruments.
SOURCE:
"Aristarchus of Sámos." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
ARCHIMEDES
“Eureka!
I have found it!”
I have found it!”
An exclamation of joy supposedly uttered as, stepping into a bath and noticing the water overflowing, he saw the answer to a problem and began the train of thought that led to his principle of buoyancy.
Archimedes was born in Syracuse, Sicily, and educated in Alexandria, Egypt. He existed between (287-212 bc).
Preeminent Greek mathematician and inventor, who wrote important works on plane and solid geometry, arithmetic, and mechanics.
In pure mathematics he anticipated many of the discoveries of modern science, such as the integral calculus, through his studies of the areas and volumes of curved solid figures and the areas of plane figures. He also proved that the volume of a sphere is two-thirds the volume of a cylinder that circumscribes the sphere.
In mechanics, Archimedes defined the principle of the lever and is credited with inventing the compound pulley. During his stay in Egypt he invented the hydraulic screw for raising water from a lower to a higher level. He is best known for discovering the law of hydrostatics, often called Archimedes' principle, which states that a body immersed in fluid loses weight equal to the weight of the amount of fluid it displaces. This discovery is said to have been made as Archimedes stepped into his bath and perceived the displaced water overflowing.
He did not hold any public office but devoted his entire lifetime to research and experiment. During the Roman conquest of Sicily, however, he placed his gifts at the disposal of the state, and several of his mechanical devices were employed in the defense of Syracuse. Among the war machines attributed to him are the catapult and—perhaps legendary—a mirror system for focusing the sun's rays on the invaders' boats and igniting them.
After the capture of Syracuse during the Second Punic War, Archimedes was killed by a Roman soldier who found him drawing a mathematical diagram in the sand. It is said that Archimedes was so absorbed in calculation that he offended the intruder merely by remarking, “Do not disturb my diagrams.” Several of his works on mathematics and mechanics survive, including Floating Bodies, The Sand Reckoner, Measurement of the Circle, Spirals, and Sphere and Cylinder. They all exhibit the rigor and imaginativeness of his mathematical thinking.
SOURCE:
“Archimedes." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
ERATOSTHENES
Eratosthenes was born in Cyrene (now Shaḩḩāt, Libya) and existed between 276?-196? BC. After becoming blind, he died in Alexandria of voluntary starvation.
He is a Greek mathematician, astronomer, geographer, and poet, who measured the circumference of the earth with extraordinary accuracy by determining astronomically the difference in latitude between the cities of Syene (now Aswān) and Alexandria, Egypt.
About 240 bc, Eratosthenes became the head of the library at Alexandria, Egypt. His calculation of the earth's circumference was only about 15 percent too large. Eratosthenes also measured the obliquity of the ecliptic with an error of only seven minutes of arc and created a catalog (now lost) of 675 fixed stars. His most important work was a systematic treatise on geography.
SOURCE:
"Eratosthenes." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
2nd Century BC
HIPPARCHUS
Hipparchus was born in Nicaea, Bithynia (now İznik, Turkey) and existed between c. 190-120 bc. He is the most important Greek astronomer of his time.
He was extremely accurate in his research, a record of which was preserved in the Almagest, the scientific treatise by the Alexandrian astronomer Ptolemy, who was greatly influenced by Hipparchus. By comparing his own celestial studies with those of earlier astronomers, Hipparchus discovered the precession of the equinoxes. His calculation of the tropical year, the length of the year measured by the sun, was within 6.5 minutes of modern measurements. Hipparchus devised a method of locating geographic positions by means of latitudes and longitudes. He cataloged, charted, and calculated the brightness of perhaps as many as 1000 stars. Hipparchus also compiled a table of trigonometric chords that became the basis for modern trigonometry.
Hipparchus developed tables of trigonometric ratios in the 2nd century bc, for which he is sometimes credited as having invented trigonometry. His method rested on the geometric theorem that if two triangles are similar, the ratio of the lengths of any two sides of one triangle equals the corresponding ratio of the other triangle. With the tables and a readily measured distance on Earth, he was able to calculate the circumference of the Earth and the distance to the Moon. He found the distance to the Moon equal to between 59 and 67 times the radius of the Earth; the correct figure is 60 times. He found the radius of the Moon to be one-third of the Earth’s radius; the present figure is 27/100.
SOURCES:
1. "Hipparchus." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
2. Pilant, Michael S. "Mathematics." Microsoft® Encarta® 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
