A person whose name finds mention in the books about Byron, and to some extent in those about Shelley, was John William Polidori, M.D.; he was Lord Byron\'s travelling physician in 1816, when his Lordship quitted England soon after the separation from his wife. I, who now act as Editor of his Diary, am a nephew of his, born after his death. Dr. Polidori figures not very advantageously in the books concerning Byron and Shelley. He is exhibited as overweening and petulant, too fond of putting himself forward face to face with those two heroes of our poetical literature, and too touchy when either of them declined to take him at his own estimation, I will allow that this judgment of Polidori is, so far as it goes, substantially just; and that some of the recorded anecdotes of him prove him deficient in self-knowledge, lacking prudence and reserve, and ignoring the distinction between a dignified and a quarrelsome attitude of mind. This book is a reprint of the original work published in 1911.