The triangle is isosceles, formed by two right triangles having sides of five, twelve, and thirteen units in length, illustrating the 47th Problem of Euclid. The triangle also represents the capstone of the unfinished pyramid and reminds the Mason of the immortality of the soul and that in eternity he will complete the capstone of his earthly labors according to the designs on the trestle-board of the Supreme Architect of the Universe. The unfinished pyramid cannot fail to remind him of the unfinished condition of the Temple when tragedy struck down its Master architect. The blaze of glory found on either side of the Great Seal cannot fail to remind the Mason of the Great Light in Masonry which is the rule and guide to faith and practice and without which no Masonic lodge can exist. It reminds him that only more light can dispel the pall of ignorance in which he stumbles until he enters the Celestial Lodge where all light is given.
Author is unknow.