The sheepskin apron, made of white lambskin, symbolizes innocence and purity, which are essential qualities required of candidates during initiation into Freemasonry. Its shape, a perfect square surmounted by a triangle, represents the union of spirit and matter, embodying the journey of the initiate from the material to the spiritual realm.
As the Entered Apprentice progresses through the degrees, the manner in which he wears the apron reflects his spiritual evolution. Initially, the triangle (spirit) is above the square (matter), indicating that the spirit has not yet descended into matter. As he advances, the triangle becomes enclosed within the square, symbolizing the integration of spirit and matter. Ultimately, as a Master Mason, the initiate experiences an ascent of the square into the triangle, representing a higher understanding and mastery of both realms.
Moreover, the apron serves as a reminder of the Masonic values of purity and moral conduct, urging the wearer to maintain a life of integrity and honor throughout his Masonic journey.