Excerpt from The Elements of Euclid: Viz. The First Six Books, Together With the Eleventh and Twelfth; The Errors, by Which Theon, or Others, Have Long Ago Vitiated These Books, Are Corrected, and Some of Euclid's Demonstrations Are Restored; Also, the Book of Euclid's Data The foundation of a science by which the investigation and discovery of useful truths, at least in mathematical learning. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.