http://en.wikipedia.org/wiki/Eye_in_the_pyramid
In 1782 the Eye of Providence was adopted as part of the symbolism on the reverse side of the Great Seal of the United States. The Eye was introduced by the original design committee of 1776, and is thought to be the suggestion of the artistic consultant, Pierre Eugene du Simitiere.
On the seal, the Eye is surrounded by the words Annuit Coeptis, meaning "It [the Eye of Providence] is favorable to our undertakings". The Eye is positioned above an unfinished pyramid with thirteen steps, representing the original thirteen states and the future growth of the country. The combined implication is that the Eye, or God, favors the prosperity of the United States.
The Great Seal is used to endorse official United States documents. As such, it is reproduced, along with the Eye of Providence, on the back of every one dollar bill.
