Fun Fact of the Day: Candles have been made out of cows, insects, and whales. Tallow (a byproduct of beef fat rendering) was popular in Europe in the Middle Ages, but candles have also been made out of wax gathered from insects and moulded with seeds, spermaceti from sperm whales, beeswax, and various different plants. Candles are now mostly made from paraffin (a solid extracted from crude oil), beeswax or soy.
When coal came into the picture, it took about 50 or 60 years to displace timber. Then, crude oil was found, and it took 60, 70 years, and then natural gas. So it takes 100 years or more for some new breakthrough in energy to become the dominant source. Most people have difficulty coming to grips with the sheer enormity of energy consumption.