Before the mid-eighteenth century, most people lived in near-complete darkness except in the presence of sunlight and moonlight. Since then, the provision of artificial light has been revolutionised by a series of innovations in appliances, fuels, infrastructures and institutions that have enabled the growing demands of economic development for artificial light to be met at dramatically lower costs: by the year 2000, while United Kingdom GDP per capita was 15 times its 1800 value, lighting services cost less than one three thousandth of their 1800 value, per capita use was 6,500 times greater and total lighting consumption was 25, 000 times higher than in 1800. The economic history of light shows how focussing on developments in energy service provision rather than simply on energy use and prices can reveal the 'true' declines in costs, enhanced levels of consumption and welfare gains that have been achieved. While emphasising the value of past experience, the paper also warns against the dangers of over-reliance on past trends for the long-run forecasting of energy consumption given the potential for the introduction of new technologies and fuels, and for rebound and saturation effects.