The Philosophy of Masonry in Five Parts (Foundations of Freemasonry Series), (Paperback)

...we have four systems of Masonic philosophy. Two are intellectual systems: First that of Preston, whose key word is Knowledge; second, that of Krause, whose key word is Morals. Two are spiritual systems: First that of Oliver, whose key word is Tradition; and second, that of Pike, whose key word is Symbolism...