Euclid They follow the same logical structure as "Elements", with definitions and proved propositions. Other works are credibly attributed to Euclid, but have been lost. The European Space Agency's (ESA) Euclid spacecraft was named in his honor. Euclid Euclid (; – "Eukleídēs", ; fl. 300 BC), sometimes given the name Euclid of Alexandria to distinguish him from Euclides of Megara, was a Greek mathematician, often referred to as the "founder of geometry" or the "father of geometry". He was active in Alexandria during the reign of Ptolemy I (323–283 BC). His "Elements" is one of the most influential works in the
Political and military events in Scotland during the reign of David I of Scotland and England", a title which acknowledged the new Scoto-Northumbrian identity of David's realm. Political and military events in Scotland during the reign of David I Political and military events in Scotland during the reign of David I are the events which took place in Scotland during David I of Scotland's reign as King of Scots, from 1124 to 1153. When his brother Alexander I of Scotland died in 1124, David chose, with the backing of Henry I of England, to take the Kingdom of Alba for himself. David was forced to engage in warfare against his rival and