Taking the words in the sequence given, an "assemblage" is a collection of individuals ; "Brethren" is used almost exclusively in solemn and scriptural language in place of "brothers"; to "meet" is to come together either in a friendly or a hostile manner ; to "expatiate" is to enlarge in discourse or to be copious in argument or discussion ; "Mysteries" are anything in the economy of divine providence which is beyond human comprehension until explained, and the "Craft" as we know it, refers to dexterity in the manual occupation of Stone-masons, applied symbolically, to the building of character.
Title
1946 - WHAT IS A LODGE OF FREEMASONS - Bro E C Pirie.