Since their earliest presence on Earth, humans have sought to make sense of their surroundings. Survival depended on understanding the behavior of a volcano, the flood cycles of a river, or the optimum time to cross a mountain pass-and humans developed ways
to record and pass on such information. As they ventured from their places of origin, by land and by sea, people acquired a broader perspective of Earth's processes and of the patterns and impact of human settlement throughout the world.
Ancient cultures such as the Egyptian, Phoenician, and Chinese amassed geographical understanding, but few of those records survive, and so the Greeks have become today's main source of early knowledge. Homer's epics, The Iliad and The Odyssey, w r i t - ten in the ninth century B.C., reveal the
Greeks as intrepid travelers and keen observers of distant lands. They also excelled in scientific inquiry. Aristotle, for example, sought to determine the size and nature of Earth in the fourth century B.C.
Geographic knowledge advanced exponentially during the heyday o f
exploration by both European and Asian explorers in the 15th, 16th, and 17th centuries. Mapping, surveying, and specimen collecting became stock activities on every voyage. In the 21st century, a few computer clicks can bring up photo images or map information for much of Earth's surface. W e take for granted the ability to get directions to almost anywhere we need to go, without our needing to plot the course on a map.
Modern science and information gathering have given geographers more insight than ever before, and modern technology allows it to be shared worldwide, but for many people the facts and terms lack a con- text. An understanding of geography, both physical and cultural, provides that context-ever more necessary and important, as global interactions and shared responsibility for Earth's future connect us all.
PTOLEMY I ANCIENT GEOGRAPHER
Born in Egypt of Greek ancestry, Claudius Ptolemy (ca A.D. 90--168) created a body
of work synthesizing the Greco-Roman world's knowledge of cartography, mathematics, and astronomy. His eight-volume Geography offered instructions and information for preparing a world atlas, including a world map and 26 regional maps. He also refined a number of map projections and provided a list of some 8,000 place- names and their coordinates. Almagest, his 13-volume treatise on astronomy, posited a geocentric model of the solar system, and his four-book Tetrabiblos tried to reconcile astrology with more scientific matters. Ptolemy's influence on geography and cartography spread through Arabic translations made by Islamic scholars and influenced Near Eastern and Western geographic and cartographic thought for centuries.
THE SCOPE OF GEOGRAPHY
Today geography is rooted in location, but it involves more than the position of place-names on a map. It integrates methods and knowledge from many different disciplines and encompasses both the physical and the social sciences. It links all these disciplines to determine why things happen in a particular location or ac- cording to particular spatial patterns.
Physical geography incorporates geology, climatology, biology, ecology, hydrology, and other natural sciences. Human geography includes cultural anthropology, economics, political science, history, demography, and other social sciences. Cartography, which is the art and science of mapmaking, provides graphic representations of geographic settings.
Geographers also use other tools in their data gathering, analysis, and representation- tools including statistics, photographs, remotely captured images (such as satellite photos), and computer-generated graphics.