On this (Emulation) tracing board, you see three, rather than two pillars. They are not the pillars that stand outside the Temple of King Solomon, but rather refer to the three principles of Wisdom, Strength and Beauty, the three classical building orders (Doric, Ionic, Corinthian), Faith, Hope and Charity, etc.
You also see Wisdom, Strength and Beauty sometimes represented by men with tools, like on this 1894 Vermont Ancient and Accepted Scottish Rite image.
Top: Emulation tracing board designed by John Harris 1849.
Bottom: Duncan’s Masonic Ritual and Monitor (1866) by Malcolm C. Duncan