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

“It is well to emphasize then, at the outset, that Masonry is a sacramental system possessing, like all sacraments, an outward and visible side consisting; of its ceremonial, its doctrine and its symbols which we can see and hear, and an inward, intellectual, and spiritual side, which is concealed behind the ceremonial, the doctrine and the symbols, and which is available only to the Mason who has learned to use his spiritual imagination and who can appreciate the reality that lies behind the veil of outward symbol.” [via]