what is the historical origin of the triple tau in the royal arch and how do standard commentators explain its symbolic meaning

The triple tau is formed by three tau crosses conjoined at their feet, serving as the primary badge and emblem of Royal Arch Masonry 1. Its historical antecedents include the widespread use of the simple tau cross as an operative mason's mark in medieval building, such as on an 11th-century column in the White Tower at the Tower of London 2.

In standard Masonic commentary, the symbol is interpreted through both sacred history and sacred geometry. Drawing upon the Book of Ezekiel, Albert C. Mackey interprets the tau as a mark of preservation and distinction, set upon those saved from destruction 1. In the Royal Arch, Mackey proposes that the triple tau serves as a mark designating and setting apart those who know and worship the true name of God from those ignorant of that mystery 1.

From a geometrical perspective, early English Royal Arch lectures explain that the intersecting lines of the triple tau form a series of right angles 1. When combined, the total value of these angles corresponds to the five Platonic solids, which symbolically represent the four elements and the sphere of the universe 1.

Symbolic commentators also interpret the emblem in trinitarian and divine terms. J. S. M. Ward notes that while the three rulers of a lodge hold gavels representing three aspects of the Deity, uniting these forms the triple tau in the Royal Arch, symbolizing the oneness of a single God 2. In this view, the emblem represents the threefold nature of the Deity—one God possessing three aspects, with each person sharing the attributes of the others 2.