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]

Consider also:

  1. “After purification come contemplation and enlightenment, which are the special subjects of the second degree. Aforetime the candidate for the Mysteries, after protracted discipline and purification enabling his mind to acquire complete control over his passions and his lower physical nature, was advanced, as he may advance himself to-day, to the study of his more interior faculties, to understand the science of the human soul, and to trace these faculties in their development from their elementary stage until he realizes that they connect with, and terminate in, the Divine itself. The secrets of his mental nature and the principles of intellectual life became at this stage gradually unfolded to his view.”
  2. “You will thus perceive, Brethren, that the F.C. degree, sometimes regarded by us as a somewhat uninteresting one, typifies in reality a long course of personal development requiring the most profound knowledge of the mental and psychical side of our nature. It involves not merely the cleansing and control of the mind, but a full comprehension of our inner constitution, of the more hidden mysteries of our nature and of spiritual psychology.”
  3. “The inward development which the second degree symbolizes is typified by the lowering of the triangular flap of the apron upon the rectangular portion below. This is equivalent to the rite of Confirmation in the Christian Churches. It denotes ‘the progress we have made in the science,’ or in other words it indicates that the higher nature of the man, symbolized by the trinity of spirit, has descended into and is now permeating his lower nature.”
  4. “In symbolical language, the N. always signifies the place of imperfection and un-development; in olden times the bodies of suicides, reprobates and unbaptized children were always buried in the north or sunless side of a churchyard. The seat of the junior members of the Craft is allotted to the north, for, symbolically, it represents the condition of the spiritually unenlightened man; the novice in whom the spiritual light latent within him has not yet risen above the horizon of consciousness and dispersed the clouds of material interests and the impulses of the lower and merely sensual life.”
  5. “The first degree is also eminently the degree of preparation, of self-discipline and purification. It corresponds with that symbolical cleansing accorded in the sacrament of Baptism, which, in the churches, is, so to speak, the first degree in the religious life; and which is administered, appropriately, at the font, near the entrance of the church, even as the act itself takes place at the entrance of the spiritual career.”