The square in the Masonic square and compass is a builder's square, used by carpenters and stonemasons to measure perfect right angles. In Masonry, this is a symbol of the ability to use the teachings of conscience and morality to measure and verify the rightness of one's actions.
The compass is used by builders to draw circles and lay off measurements along a line. It is used by the Masons as a symbol of self-control, the intention to draw a proper boundary around personal desires and to remain within that boundary line.
The letter G usually found in the center of the square and compass is said to represent "geometry" or "God."
