the 47th problem of Euclid is a geometric principle from antiquity. It provides insight into the right angle and is one of the basic principles for the bricklayer’s profession. Euclid (300 BC) was a Greek mathematician, often referred to as the “founder of geometry”, and always been associated with the history of Freemasonry. His Elements is one of the most influential works in the history of mathematics The well-known forty-seventh (47th) problem in this book, although not discovered by him, but long credited to Pythagoras, has been adopted as a symbol in Masonic instruction.
