What is a Blue Lodge?
This discourse is designed to give you a brief introduction to the Craft and the mainstay of Freemasonry, the Blue Lodge, or symbolic Lodge, as it is more properly known. Every man's journey into Freemasonry begins in a symbolic Lodge, where he receives the first three Degrees in Masonry. These are known, respectively, as the Entered Apprentice, Fellowcraft and Master Masons Degrees. Some refer to them as the 1st, 2nd and 3rd Degrees. Only the most profound ritual and symbolism characterizes our Degrees, designed to open the eyes and mind to a higher ideal.
Masonry is a closed society, not open to the general public, but rather to persons of like persuasions and ideals. While no two people are alike, they can share a common belief in the Brotherhood of man and in ONE who we in Masonry refer to as the Supreme Architect of the Universe. The tenets of Masonry are Brotherhood, Relief and Truth. We espouse all men being equal, regardless of their worldly wealth or position, and attempt to relieve our fellow man’s woes and tribulations, again regardless of membership in the Fraternity. We also practice the virtue of Truth. This may be the hardest of all, because it is often easier to tell a little white lie than to confront one with the truth.
Masonic Lodges, also known as Blue Lodges, are where Freemasons meet for meetings. These Masonic Blue Lodges are in many towns and cities throughout the world. You can easily identify where Freemasons meet by the Square and Compass emblem displayed on the building, either mounted on a wall or sign. Local Blue Lodges are organized under a Grand Lodge. Each state has a Grand Lodge, which presides over the operation of all Blue Lodges within that state. Joining a Blue Lodge is usually done by meeting a Brother from the Lodge that you are interested in joining. This Brother will be your guide to help you navigate the membership and initiation process of his Lodge. No man may become a Freemason without first being recommended by two Brothers and then having been found to be of good report by the Lodge's Investigation Committee.
The ritual practiced by the symbolic lodge is called York Rite, and follows into the Royal Arch Chapter, thence into the Commandry. On the other side of the coin is the Scottish Rite, which opens another door of Masonry.
Source: http://www.masonicworld.com/education/files/mar05/blue_lodge_masonry.htm
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