For obvious reasons, the pyramid is a symbol of an ancient and long-enduring work of human creation. But this is an incomplete pyramid, built up thirteen layers from the base, marked 1776, up towards an eye in a floating triangle, known as the Eye of Providence, a centuries-old symbol of the Trinity and the all-seeing God.[4]
Taken together, it means Providence approves of the work we started in 1776, that we have built up with our thirteen states, that will continue to build towards His approval, and which will endure through the ages.
The first form of this design was proposed by a Congressional design commitee in 1776, and this form was officially adopted as the Great Seal by Congress 1782.
Freemasonry adopted it as their symbol in 1797.