Boswell: But, Sir is it not somewhat singular that you should happen to have Cocker's Arithmetic about you on your journey? Dr. Johnson: Why, Sir if you are to have but one book with you upon a journey, let it be a book of science. When you read through a book of entertainment, you know it, and it can do no more for you; but a book of science is inexhaustible.
James Boswell (1859). “Journal of a tour to the Hebrides with Samuel Johnson LL.D.: containing some poetical pieces by Dr. Johnson, relative to the tour, and never before published ... : with an authentic account of the distresses and escape of the grandson of King James II. in the year 1746”, p.104
