light and could be used to record the images. The discovery of the century It is usual to date the birth of photography to the introduction of the Daguerreotype in 1839, but it could be said to have been essentially a reinvention - most of the technique was already known. The lens was known, the camera was known, and the reaction of silver salts when exposed to light had been known for a hundred years. What made it new was that everything was brought together, while the problem of making the silver salts sufficiently sensitive to light was solved, and a method was found of fixing the pictures so that they did not darken further when exposed to more light. If you tried to patent this under today's rules, it would be a matter of arguing for a second class patent, or a patent on a new application of an already known technique. Still, contemporaries saw photography as the invention of the century, a reasonable view considering the role photography would come to play. The importance of the picture Before photography's breakthrough, pictures were rare and exclusive. When King Gustaf III of Sweden employed Pehr Kraft the Elder to paint the portrait of Bellman, his pay was the equivalent of the price of a luxury car today. Accurate portraits and other sophisticated pictures were reserved for the upper classes. I was reminded of the real importance of this when studying some eighteenth-century texts a couple of years ago. One text