What are the three Great Lights in Freemasonry?

The three Great Lights are the Volume of the Sacred Law, the Square, and the Compasses, with the Volume of the Sacred Law held as the chief among them, as the United Grand Lodge of England states.

In his commentary on their symbolic union, Wilmshurst interprets the Sacred Volume as the external emblem of the unwritten Eternal Word or Logos, which forms the underlying ground and spiritual base of human existence 1. Upon this foundation rests the Square, which he takes as a symbol of the human soul generated out of that Divine Word—originally created balanced and perfect, and represented geometrically in ancient symbolism as an inverted triangle 1. The Compasses, interlaced with the Square, represent the Spirit of the Soul, signifying its active functional energy or fire 1. For Wilmshurst, the intimate conjunction of all three lights connotes the functional relationship between the Divine source, the receptive human soul, and the active spiritual energy that animates it 1.