“That being a Point from which a Freemason cannot err”: explain

The phrase refers ritualistically to "the Centre" or the symbol of the point within a circle, carrying both a practical operative origin and distinct speculative interpretations 121.

Operatively, Carl H. Claudy traces the phrase to the medieval stonecutters' method of testing wooden squares for true right angles. By drawing a triangle inside a circle using its diameter as the base, any point chosen on the circumference forms a perfect right angle when connected to the ends of that line 2. By regularly checking their wooden tools against this unvarying geometric truth, ancient Masters ensured that neither their tools nor their building work could "materially err" 2.

In speculative Masonry, this geometric test is transformed into a emblem for moral self-governance 2. Claudy explains that the point within a circle serves speculatively as a secret test for the rectitude of a Mason's conduct and intentions, ensuring his actions remain properly circumscribed and aligned with virtue 2.

Walter Leslie Wilmshurst gives the phrase a mystical reading, regarding the formal ritual definition of the Centre as intentional "puzzle-language" designed to prompt deeper reflection 1. To Wilmshurst, the Centre represents the vital, immortal principle or divine spirit residing at the core of human nature 1. By learning to "open the Lodge upon the centre" of oneself and acting from that inward spiritual reality—bounded by divine law and wisdom—a Mason aligns with eternal truth and cannot spiritually err 1.