Optical connections: The all-seeing eye

An unblinking eye surrounded by rays of light radiating out from it, sometimes pictured within a triangle, sometimes on top of a pyramid. A familiar, if mysterious, symbol. An example of which is seen and handled every day by millions of people in the form depicted on the reverse of the US one-dollar bill. Such is the ‘All-seeing Eye’, or ‘Eye of Providence’ as it is sometimes known. But what exactly does it symbolise? From where does it originate? And is there any optical significance relating to it?

The idea of the all-seeing eye is quite ancient. Some connect it with the Egyptian symbol of the Eye of Horus, but the more likely origin is descriptions of the Divine gaze watching over all humanity’s deeds that are to be found in Old Testament biblical texts such as the Book of Psalms and Ecclesiastes. ‘Behold, the eye of the Lord is upon them that fear Him, upon them that hope in His mercy’, (Psalms) and ‘The eyes of the Lord are in every place, beholding the evil and the good’, (Ecclesiastes) are just two of many quotations that illustrate the point.