why does a Royal Arch Chapter have three Principals instead of a single Master

The governance of a Chapter by three Principals rather than a single Master expresses both a symbolic doctrine of spiritual unity and a historic model of conjoint rule.

In terms of symbolism, Walter Leslie Wilmshurst reads the triad of Principals—Zerubbabel, Haggai, and Joshua—as personifications of the threefold aspects of monadic Spirit: central coordinating power, passive insight, and active executive capacity 1. In this interpretation, the middle term differentiates into passive and active aspects while all three act conjointly as one 1. They represent the summit of human nature on the spiritual plane—holy, royal, and supreme—forming a complete unity rather than an individual hierarchy 1.

Historically, under the English system, the three presiding officers are designated as the First, Second, and Third Principals (representing King, Prophet, and Priest) 2. Each Principal undergoes a distinct installation and receives an installing degree, rather than taking sole charge as a Master does 2.

This tradition of conjoint governance continues in contemporary practice. Chapters are presided over jointly by three Principals, with the First Principal acting as first among equals, as the Grand Lodge of India and the United Grand Lodge of England both state on their official sites.

The Three Principals of a Royal Arch Chapter represent the historical personages of Zerubbabel, Haggai, and Joshua, who correspond to the roles of King, Prophet, and Priest 2.

Beyond their historical identification, Walter Leslie Wilmshurst interprets the three Principals as personifications of the threefold attributes of the human spirit at its highest plane 1. In his reading, the triad represents monadic Spirit in its distinct attributes of Holiness, Royal Supremacy, and Functional Power 1.

Zerubbabel, as the First Principal and central term, signifies the apex and directive focus of man's spirituality—the inner prince or higher coordinating element that rises above the chaotic multitude of ordinary desires 1. From this central coordinating power, the spiritual principle differentiates into passive and active aspects 1.

Haggai, the Prophet, personifies the passive, contemplative aspect of the spirit 1. He represents intuition, spiritual insight, and omniscience, projecting foreglimpses of divine truth into the lower human intelligence 1.

Joshua, the High Priest, personifies the active, executive aspect of the spirit 1. Representing divine salvation and righteousness, this principle functions as a mediator to transmute, redeem, and subdue man's lower nature 1.

Together, the three act conjointly as a single sovereign unit, symbolizing the summit of human nature on the spiritual plane—holy, royal, and supreme—realigned in perfect unity 1.