the three letters ‘S’ mean Science adorned with Sagacity makes the Saintly Man. (There are various variations of this interpretation in early rituals.
From a 28th degree Ancient Ancient Accepted Scottish Rite tracing board.
A variation to this tracing board can be found in Lennhoff. He calls it a Russian tracing board.
Top: A. & A. R. The intermediate Degrees 19º – 29º A.C.F. Jackson (1982)
Bottom: Politische Geheimbünde Eugen Lennhoff 1934