Melvin Bragg presents an excellent and thought provoking series of radio programs [In Our Time] on science and culture. Todays program was about the history of lenses and lens making - their impact on science. Starting from the Greeks/Romans, passing through the arabs to spectacle makers, via Galileo, to Kepler, Newton Herschel and the microscopists.
For this week [1st march 2007], you can listen again at the main in our time page, otherwise, it will be in the archives for download.
I suppose this is not strictly an essay - but this program does give a really good overview on optics and its place in history. If you do listen be warned: you will want to kick one of the three speakers - but I'll leave that to you to guess which one.