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
The Oxford Textbook of Medicine Research in Health programme. The "Oxford Textbook of Medicine" is edited by: In total, there are 750 contributors to the textbook. The Oxford Textbook of Medicine The Oxford Textbook of Medicine is an international textbook of medicine. First published in 1983, it is now in its fifth edition. It is primarily aimed at mature physicians looking for information outside their area of particular expertise, but widely used as a reference source by medical students and doctors in training, and by others seeking authoritative accounts of the science and clinical practice of medicine. The "Oxford Textbook of Medicine" is available in