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

“No! the death to which Masonry alludes, using the analogy of bodily death and under the veil of a reference to it, is that death-in-life to a man’s own lower self which St. Paul referred to when he protested ‘I die daily’. It is over the grave, not of one’s dead body but of one’s lower self, that the aspirant must walk before attaining to the heights.” [via]