In the Middle Ages, surgery was performed by barbers due to their skill with sharp instruments. In the mid-19th century, a 'grand exhibition' of the effects of laughing gas inadvertently led to the discovery of anesthesia. Three decades later, Louis Pasteur enjoyed a crucial breakthrough in his search for vaccinations because his assistant decided, against his orders, to take a vacation. Here, cardiac surgeon and professor of medical history Jean-Noël Fabiani stitches together the most significant and intriguing episodes from the history of medicine, from chance breakthroughs to hard-fought scientific discoveries.