One of the earliest forms of portable illumination, candles have served vital functions for humankind throughout history, a fact chronicled through the discovery of candles or candle-like objects in virtually every society. Historians believe the original candle may have been invented by primitive men who dipped dried branches in animal fat, thus producing a slow-burning and reliable source of light. Reliefs belonging to the ancient Egyptians depict the use of candles by writers and philosophers who worked well after sundown. These early candles were most likely developed from tapers that were made of fibrous materials mixed with wax or tallow (the white, nearly tasteless fat of cattle or sheep that was also used to make soap, margarine, and lubricants). As far back as 3000 B.C. dish-shaped candles were used on the island of Crete.