what is the moral lesson of the working tools in the second degree

The working tools associated with the second degree—principally the Plumb, the Square, and the Level—teach lessons of moral rectitude, conscience, and upright conduct 13.

The Plumb teaches steadfastness in truth and moral rectitude 1. Just as an operative builder relies on the plumb line to establish a true perpendicular, the speculative Mason is instructed to remain upright in character, neither bending beneath the frowns of adversity nor yielding to the seductions of prosperity 1. William Preston defined the tool's symbolism as teaching the criterion of rectitude, avoiding dissimulation in speech and action, and directing one's steps in the path toward immortality 1. Carl Claudy emphasizes that the Plumb, linked to the passage from the Book of Amos read during the ceremony, instructs a Mason to judge his own work and the actions of others using a true internal standard rather than superficial or distant judgment 2.

The Square serves as an emblem of morality, fair dealing, and honour 3. It acts as the try square of conscience, against which a Mason tests and regulates his every word and act 3. Applied symbolically to fraternal conduct, it teaches that while Masons meet upon the level, they must act with uprightness so that when they part upon the square, they carry away no hypocrisy or resentment 1.

William Preston is credited with originating the elaborated, philosophical system of lectures that defines the rich symbolic instruction of the Fellow Craft degree 1.

Before the last quarter of the eighteenth century, the lectures used in English lodges were brief, unscientific, and meager in detail, lacking much of the symbolic commentary used today 1. Popular traditions occasionally attributed early ritual revisions to figures like Martin Clare or Thomas Dunckerley, but no historical evidence supports their involvement 1. It was Preston who thoroughly revised and largely rewrote the lectures, introducing the structured, philosophical system and full explanations of symbolism that replaced the older, plain instruction 1.