What is the significance of the lambskin apron in Freemasonry?

The lambskin apron is presented to a candidate upon initiation as the first gift, first symbol explained, and first tangible evidence of admission into the Fraternity 1. Its material, unspotted lambskin, constitutes its primary symbolic character, representing innocence, purity of life, and rectitude of conduct necessary to gain admission into the Celestial Lodge above 12. Substituting other fabrics, such as silk or satin, destroys this essential emblematic character 1.

Known as the "badge of a Mason," the apron is held to be more ancient than historic orders of chivalry and honor, such as the Golden Fleece, Roman Eagle, or Star and Garter 121. The practice of symbolic investiture with an apron or girdle has antecedents in ancient rites, including the Hebrew priesthood, the Essenes, and the mysteries of Persia, India, and Japan 12.

Beyond symbolizing innocence, the physical geometry of the apron holds symbolic meaning. Wilmshurst observes that when worn in the First Degree with the flap raised, the apron forms a five-cornered shape representing the five senses, while combining a three-sided triangular top (the soul) and a four-sided quadrangular bottom (the body) to yield seven, denoting the seven-fold constitution of man 3. Wilmshurst also interprets the physical human body itself as the true "badge of innocence" that the outer lambskin signifies 3.

A Mason never parts with his apron throughout his Masonic career; though its ornamentation changes as he advances in degree or office, its underlying substance remains 1. It is worn throughout an honorable life and, according to traditional ritual addresses, is placed upon the Mason's coffin at death 21.