The Deeper Symbolism of Freemasonry from The Meaning of Masonry by Walter Leslie Wilmshurst.

“And so, as the sign peculiar to the degree suggests, he endeavours to examine and lay bare his heart, to cast away all impurity from it, and he stands, like Joshua, praying that the light of day may be extended to him until he has accomplished the overthrow of his own inward enemies and of every obstacle to his complete development.” [via]