130 Ptolemy writes the _Almagest_ which was the standard work on optics for centuries. Subjects treated included the persistence of vision, the laws of reflection and studies of refraction. 170 Galen, an early medical authority, considers the problems of vision, fundamental to the scientific application of light to create the illusion of motion. 510 Boethius tries to measure the speed of light. Charges of treason and magic result in his decapitation in 525 at the order of his former patron, King Theodoric, Ostrogoth dictator of Italy. 750 Geber, Arabian alchemist, notes the effect of light on silver nitrate, a basis of photography. 870 Alkindi, an Arab, advances scientific learning, including work in the fields of astronomy and navigation. 1010 Alhazen, greatest of the Arab scientists in optics, advances the art-science of magic shadows and succeeds Ptolemy as the standard authority. 1020 Avicenna, another Arab, studies the movements of the eye in vision. 1175 Averroës, famed Arab philosopher, studies vision and eye movement. 1267 Roger Bacon, English Friar, describes the use of mirrors and lenses and attacks necromancers who use such devices to deceive the people. 1270 Witelo, a Pole called Thuringopolonus, writes on all phases of optics and with Bacon dominates experiments in this field for generations. 1275 St. Albertus Magnus, Dominican scholar and teacher of St. Thomas Aquinas, takes special interest in the rainbow and assigned a finite but very great velocity to light. 1279 John Peckham, English Franciscan and alchemist, in his _Perspectiva Communis_ points out that the rays of the sun can be shown in any desired place, indicating a knowledge of the “dark room.” 1300 Spectacles are introduced in Italy. 1438 Gutenberg develops printing from movable type which hastens the exchange of all knowledge, an aid to the growing interest in all light and shadow problems. 1450 Leone Battista Alberti, an Italian cleric and architect, designs the _camera lucida_, a light and shadow device similar to a large box camera for the use of artists in copying, drawing and nature. 1464 Nicholas of Cusa writes the first book about eye glasses. 1500 Leonardo da Vinci sets down the first accurate description of the portable or “dark room” _camera obscura_ and shows its relation to the human eye. 1520 Francesco Maurolico, a mathematician and astronomer of Messina, develops the scientific but not experimental principles of light as reflected by mirrors and the use of light theatres. The next year he describes the construction of a compound microscope.