The Life of Samuel Johnson, LL.D. (1791) is a biography of Dr. Samuel Johnson written by James Boswell. The work was a popular and critical success when first published. It is regarded as an important stage in the development of the modern genre of biography; many have claimed it as the greatest biography written in English, but some modern critics object that the work cannot be considered a proper biography. While Boswell's personal acquaintance with his subject only began in 1763, when Johnson was 54 years old, Boswell covered the entirety of Johnson's life by means of additional research. The biography takes many critical liberties with Johnson's life, as Boswell makes various changes to Johnson's quotations and even censors many comments. Nonetheless, modern biographers have found Boswell's biography an important source of information on Johnson and his times.