Preclarissimus liber elementorum Euclidis perspicacissimi
Eucleides(Euclid, c330-235 B. C.)
 After the death of Alexander the Great, his generals battled against each other. Ptolemaios (Ptolemy), who was one of the generals, defeated the remaining generals and founded the Ptolemy dynasty (whose last Queen was the famous Cleopatra) with its capital as Alexandria in Egypt. In an attempt to establish Alexandria as the academic center of the world, Ptolemy gathered famous scholars, supported their scientific research, and finally succeeded in making Alexandria a more significant academic center than Athens in Greece. Euclid contributed to Ptolemy’s achievement, became the head of the mathematics department of a great library and a research center, the “Museion,” established by Ptolemy I. Euclid gathered all the previous achievements of Greek geometry and summarized them into this book. In this context, the term “summarized” does not mean that he simply reported the previous achievements. Instead, he established some simple axioms (e.g., the axiom stating that “parallel lines never intersect”) and derived more than 500 theorems based on these axioms. Thus, he combined all the geometrical knowledge into a consistent and logical system. Euclid’s system was observed to be complete even though Apollonius and Archimedes added new results to Euclid’s theorems. Hence, this book was used as a textbook throughout the middle ages and the early modern era. Even now, the geometrical concepts that are taught in junior high schools and high schools are based on the Euclidean geometry. Therefore, it can be concluded that this book has been used for the longest time among all the textbooks worldwide. The Euclidean geometry was considered to be the only true geometry before Lobachevsky, Bolyai, Lehmann, and others created the so-called non-Euclidean geometry system during the 19th century.