Masonic Square and Compass Blue & White embroidered Patch
The Square and Compasses (or, more correctly, a square and a set of compasses joined together) is the single most identifiable symbol of Freemasonry. Both the square and compasses are architect's tools and are used in Masonic ritual as emblems to teach symbolic lessons. Some Lodges and rituals explain these symbols as lessons in conduct: for example, that Masons should "square their actions" and learn to "circumscribe and keep us within due bounds toward all mankind".  However, as Freemasonry is non-dogmatic, there is no general interpretation for these symbols (or any Masonic symbol) that is used by Freemasonry as a whole.  As measuring instruments, the tools represent judgment and discernment.  Provided by Wikipedia