In the scholarly realm, Hellenistic thinkers made advances in mathematics, astronomy, and mechanical design. The most notable of the Hellenistic astronomers was Aristarchus of Samos (ca. 310–230 B.C.E.). Aristarchus rightly concluded that the sun is far larger than the earth and that the stars are enormously distant from the earth. He also argued against Aristotle’s view that the earth is the center of the universe, instead propounding the heliocentric theory — that the earth and planets revolve around the sun. His theory was discussed for several centuries, then forgotten, and was resurrected in the sixteenth century C.E. by the brilliant Polish astronomer Nicolaus Copernicus.

In geometry Euclid (YOO-kluhd) (fl. ca. 300 B.C.E.), a mathematician living in Alexandria, compiled a valuable textbook of existing knowledge. His The Elements of Geometry became the standard introduction to the subject. Generations of students from antiquity to the present have learned the essentials of geometry from it.

The greatest thinker of the Hellenistic period was Archimedes (ahr-kuh-MEE-deez) (ca. 287–212 B.C.E.). A clever inventor, he devised new artillery for military purposes. In peacetime he created the water screw to draw water from a lower to a higher level. (See “Individuals in Society: Archimedes, Scientist and Inventor.”) He also invented the compound pulley to lift heavy weights. His chief interest, however, lay in pure mathematics. He founded the science of hydrostatics (the study of fluids at rest) and discovered the principle that the weight of a solid floating in a liquid is equal to the weight of the liquid displaced by the solid.

Archimedes willingly shared his work with others, among them Eratosthenes (ehr-uh-TOSS-thuh-neez) (285–ca. 204 B.C.E.), who was the librarian of the vast Ptolemaic royal library in Alexandria. Eratosthenes used mathematics to further the geographical studies for which he is most famous. He concluded that the earth is a spherical globe and calculated the circumference of the earth geometrically, estimating it at about 24,675 miles. He was not wrong by much: the earth is actually 24,860 miles in circumference.

As the new artillery devised by Archimedes indicates, Hellenistic science was used for purposes of war as well as peace. Theories of mechanics were applied to build military machines. Fully realizing the practical possibilities of the first effective artillery in Western history, Philip of Macedonia had introduced the machines to the broader world in the middle of the fourth century B.C.E. The catapult became the most widely used artillery piece. As the Assyrians had earlier, engineers built siege towers, large wooden structures that served as artillery platforms, and put them on wheels so that soldiers could roll them up to a town’s walls. Generals added battering rams to bring down large portions of walls. If these new engines made warfare more efficient, they also added to the misery of the people, as war often directly involved the populations of cities. War and illness fed the need for medical advances, and doctors as well as scientists combined observation with theory during the Hellenistic period. Herophilus, who lived in the first half of the third century B.C.E., worked in Alexandria and studied the writings attributed to Hippocrates. He approached the study of medicine in a systematic, scientific fashion: he dissected dead bodies and measured what he observed. He was the first to accurately describe the nervous system and studied the liver, lungs, uterus, and brain, which he considered the center of intelligence. His students carried on his work, searching for the causes and nature of illness and pain.

Medical study did not lead to effective cures for the infectious diseases that were the leading cause of death for most people, however, and people used a variety of ways to attempt to combat illness. Medicines prescribed by physicians or prepared at home often included natural products blended with materials understood to work magically. People in the Hellenistic world may have thought that fate determined what would happen, but they also actively sought to make their lives longer and healthier.