This emblem appears throughout both Bacon's work and the Shakespeare plays. The Double A was homage to AthenA, the Greek Goddess of Wisdom, and symbolized two stairways to Masonic illumination. Her ideals were adopted by the FreeMasons as their main goal, that of bringing the world from darkness into light. This is symbolized by their light and dark scroll devices.
SirBacon.org - Sir Francis Bacon's New Advancement of Learning