Parallel (geometry) as a pair of straight lines in a plane which do not meet appears as Definition 23 in Book I of Euclid's Elements. Alternative definitions were discussed by other Greeks, often as part of an attempt to prove the parallel postulate. Proclus attributes a definition of parallel lines as equidistant lines to Posidonius and quotes Geminus in a similar vein. Simplicius also mentions Posidonius' definition as well as its modification by the philosopher Aganis. At the end of the nineteenth century, in England, Euclid's Elements was still the standard textbook in secondary schools. The traditional treatment of geometry was being
Library of Alexandria who had studied at the Library of Alexandria and their students continued to conduct research and write treatises, but most of them no longer did so in association with the Library of Alexandria. A diaspora of Alexandrian scholarship occurred, in which scholars dispersed first throughout the eastern Mediterranean and later throughout the western Mediterranean as well. Aristarchus's student Dionysius Thrax ( 170– 90 BC) established a school on the Greek island of Rhodes. Dionysius Thrax wrote the first book on Greek grammar, a succinct guide to speaking and writing clearly and effectively. This book remained the primary grammar textbook for