The Masonic Keystone has eight letters engraved; HTWSSTKS, which stands for ‘Hiram The Widow’s Son Sent To King Solomon.’ Third-degree masons study the legend of a person called Hiram Abiff, also known as the widow’s son.

Legends narrate that Hiram was the chief architect in constructing the Temple of Solomon. He was mercilessly killed for failing to surrender the secret Masonic passwords. Mason, therefore, holds him as a symbol of loyalty.

His story emphasizes the importance of keeping the craft’s secret dearly.

The letters HTWSSTKS are carved on the grave headstones of Royal Arch masons who surpassed the third-degree level.