Transmission of the Greek Classics on music ("De institutione musica libri quinque", unfinished) contributed to medieval education. "De arithmetica", begins with modular arithmetic, such as even and odd, evenly even, evenly odd, and oddly even. He then turns to unpredicted complexity by categorizing numbers and parts of numbers. His translations of Euclid on geometry and Ptolemy on astronomy, if they were completed, no longer survive. Boethius made Latin translations of Aristotle's "De interpretation" and "Categories" with commentaries. These were widely used during the Middle Ages. In the Western Provinces (what today is considered the Western Europe's heartland), the collapsing Roman empire lost many Greek manuscripts
Lighthouse of Alexandria this mole, and the Ras el-Tin promontory represents all that is left of the island of Pharos, the site of the lighthouse at its eastern point having been weathered away by the sea. The lighthouse was constructed in the 3rd century BC. After Alexander the Great died, the first Ptolemy (Ptolemy I Soter) announced himself king in 305 BC, and commissioned its construction shortly thereafter. The building was finished during the reign of his son, the second Ptolemy (Ptolemy II Philadelphus). It took twelve years to complete, at a total cost of 800 talents, and served as a prototype for