Where it all began...

The Golden Ratio is a proportion that has intrigued numerous intellectuals of diverse interests since antiquity. Although the first clear definition was derived by Euclid around 300 B.C., it was already used by the Egyptians in constructing the Pyramids at Giza.

Note: The Greeks usually attributed the discovery of the ratio to Pythagoras.

The common symbol for the Golden Ratio, in the professional mathematical literature, is the Greek letter 'tau' meaning "the cut" or "the section". However, the American Mathematician Mark Barr gave the ratio the name 'phi' at the beginning of the twentieth century to honor the great Greek sculptor, Phidias.

To View the timeline of the Golden Ratio, have a look at this link:
http://en.wikipedia.org/wiki/Golden_ratio#Timeline

The Golden Ratio frequently appears in geometry especially regular pentagrams and pentagons. It is this that fascinated ancient Greek mathematicians to first study the Golden Ratio. It is found in art and architecture, especially in ancient Greek temples. During the Renaissance in Italy, many scientists and artists such as Leonardo Da Vinci were drawn to mathematics and its relationship to the spiritual and physical order of the universe. This is why they called the Golden Ratio the "divine proportion".