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

“By perfecting his conduct, by struggles against his own natural propensities, the candidate is working the rough ashlar of his own nature into the perfect cube, and I would ask you to observe also that the cube itself contains a secret, for unfolded, it itself denotes and takes the form of the cross.” [via]

Consider also:

  1. “Here again the symbolism of our work becomes extremely profound and interesting. He who desires to rise to the heights of his own being must first crush and crucify his own lower nature and inclinations; he must perforce tread what elsewhere is described as the way of the Cross; and that Cross is indicated by the conjunction of those working tools (which when united form a cross); and that ‘way’ is involved in the scrupulous performance of all that we know those working tools signify.”
  2. “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.”
  3. “And hence also it is that the Lodge has seven principal officers, and that a Lodge, to be perfect, requires the presence of seven brethren; though the deeper meaning of this phrase is that the individual man, in virtue of his seven-fold constitution, in himself constitutes the ‘perfect Lodge,’ if he will but know himself and analyse his own nature aright.”
  4. “But upon entering this world, the soul must needs assume material form; in other words it takes upon itself a physical body to enable it to enter into relations with the physical world, and to perform the functions appropriate to it in this particular phase of its career. Need I say that the physical form with which we have all been invested by the Creator upon our entrance into this world, and of which we shall all divest ourselves when we leave the Lodge of this life, is represented among us by our Masonic apron?”
  5. “By the assistance of these lesser lights within us, a man is enabled to perceive what is, again symbolically, called the ‘form of the Lodge,’ i.e. the way in which his own human nature has been composed and constituted, the length, breadth, height and depth of his own being.”