I was a little upset at this book for having to end. Holmes writes with a palpable compassion for his subjects. The book's major players are so fully animated that I couldn't help but feel a sadness at parting with these historical figures, most of whom I had never heard of before and all of whom, of course, had been dead for more than a century before I was born. I think that the way Holmes structured the book, with the same kind of intricate plot architecture as a good 19th century novel, really contributed to this feeling; the people introduced in the opening chapters are still there, growing old and being swept aside by the inevitable tides of the decades, in the final ones. He is a master at seamlessly weaving in excerpts from his primary sources - letters, diaries, scientific log books - and also not afraid to throw in some scatological references, of a academic bent.