In today's world of specialisation, it's virtually impossible to contribute to more than one area of study. Even two centuries ago this was very difficult, but in The last man who knew everything
Andrew Robinson tells the story of Thomas Young, who was a prime example of such a polymath. We hear of how Young was an expert in many areas, in particular overthrowing Newton's ideas of light corpuscules with his wave based theory, and deciphering Egyptian heiroglyphics from the Rosetta stone. Young also contributed articles to the Encyclopedia Britannica on a wide range of subjects, and all the while had to spend most of his time on his 'day job' as a doctor.
Young was sometimes criticised for being a dilettante. Robinson shows how this criticism was unfounded - how Young was as much an expert as those who specialised in the subjects concerned, and how such a criticism was most likely to come from those whose ideas were challenged by Young. He may not have been able to develop his ideas into a systematic whole, but that is not unusual for the originator of novel theories. I'd recommend this book to anyone interested in the work of Young or in the problems of being a polymath, either two centuries ago or today.