In each of the Degrees of Freemasonry, certain implements of the Operative Art are consecrated to the Speculative Science, and adopted to teach as symbols lessons of morality. With these the Speculative Freemason is taught to erect his spiritual Temple, as his Operative predecessors with the same implements so constructed their material Temples. Thus they are known as Working Tools of the Degree. They vary but very slightly in the various Rites, but the same symbolism is preserved. The principal Working-Tools of the Operative Art that have been adopted as symbols in the Speculative Science, confined, however, to Ancient Craft Masonry, and not used in the higher Degrees, are the Twenty-four-inch Gage, Common Gavel, Square, Level, Plumb, Skirret, Compasses, Pencil, Trowel, Mallet, Pickax, Crow, and Shovel. See them under their respective heads in this encyclopedia.
- Source: Mackey's Encyclopedia of Freemasonry