I always thought that he did himself injustice in his account of what he had read, and that he must have been speaking with reference to the vast portion of study which is possible, and to which few scholars in the whole history of literature have attained; for when I once asked him whether a person whose name I have now forgotten, studied hard, he answered ‘No, Sir. I do not believe he studied hard. I never new a man who studied hard. I conclude, indeed, from the effects, that some men have studied hard, as Bentley and Clarke’. Trying him by that criterion upon which he formed his judgement others, we may be absolutely certain, both from his writings and his conversation, that his reading was very extensive. Dr. Adam Smith, than whom few were better judges on this subject, once observed to me, that ‘Johnson knew more books than any man alive’. He had a peculiar facility in seizing at once what was valuable in a book, without submitting to the labour of perusing it from beginning to end. He had, from the irritability of his constitution, at all times, and impatience and hurry when he either read or wrote.
—Boswell (Life of Johnson, p. 34, somewhere in 1729)