As the name suggests Koestler's central thesis is that scientific progress has been largely dependant on happenstance and mistakes. He explores the thesis by taking the reader on a historical tour, starting with pre-history, ranging through the Greeks and ending as Newton arrives on the stage. He concentrates particularly on Copernicus, Kepler and Galileo for much of the book and reveals much about this period that I certainly did not know and found fascinating. One example is just how close Kepler came to formulating the law of Gravity before Newton.

I cannot recommend this book highly enough. I would make it compulsory reading for any student of science and recommended reading for any student of anything. My hypothetical top 10 books changes over time like most people - as I read new works which enter the chart. I first read Sleepwalkers 20 years ago and it has never been out of my list and has never been lower than 3.

Do yourself a great favour and buy a copy - I promise that you will thank me for it later.