DIVESTED OF ALL MINERALS AND METALS
"And there thou shalt build an altar unto the Lord thy God,..."
Deut. 27:5
Candidates for degrees in Freemasonry are required to enter a Masonic lodge without any metallic substances on their person. They are also instructed that King Solomon's Temple was erected without the aid of any iron or metallic tools.
Eventually they learn about the Masonic importance of the biblical character Tubal-cain, who is described in the book of Genesis as the first artificer in metals. Explanations about each of these subjects are provided during the ceremonies, but those explanations are merely preliminary to the deeper meanings, which are veiled in the mysteries of the Craft that each candidate must explore for himself.
If the science of alchemy may be said to refer to the transformation of substances and elements (ie lead into masonic gold), then the philosophy of alchemy may be said to similarly pertain to the transformation of men from non-spiritual to spiritual beings.
As such, the importance of alchemy to Freemasons is not so much the substantive alchemical philosophy as it is what that substantive philosophy actually symbolizes. It is not enough to merely understand that it symbolizes change. It is far more important to understand that it symbolizes the need to learn how to change and how to make the necessary changes.
Freemasonry selects tools of architecture, or tools of iron from which to teach wise and serious truths. The plumb, level and square are implements used for construction and together with the other several tools of iron selected by the Craft teach a candidate the what and how of transforming himself from a non-spiritual to a spiritual being.
For example the plumb admonishes us to walk uprightly before God, which means that we must learn and follow His laws, which laws include the laws of Nature. The level teaches us that we are traveling a path that eventually will lead us to a world beyond this material existence - a place from whose bourne no traveler returns. We are thereby taught that something is expected of us; something other than living a life filled with luxury and indolence. The square symbolizes justice, equality and truth and thereby teaches the importance of acting fairly toward all men at all times.