The Freemasons have many ranks but the highest is the 33rd degree, and this picture shows this. It starts from the entered apprentice to a grand lodge master. there are many of graphs ;like this that will show all the different types of masons.
Twain was a Freemason. He belonged to Polar Star Lodge No. 79 A.F., based in St. Louis. He was initiated an Entered Apprentice on May 22, 1861, passed to the degree of Fellow Craft on June 12, and raised to the degree of Master Mason on July 10.