"BOSWELL. 'But, sir,'tis like walking up and down a hill; one man will naturally do the one better than the other. A hare will run up a hill best, from her fore-legs being short; a dog down.' JOHNSON. 'Nay, sir; that is from mechanical powers. If you make mind mechanical, you may argue in that manner. One mind is a vice, and holds fast; there's a good memory. Another is a file; and he is a disputant, a controversialist. Another is a razor; and he is sarcastical.'"
— Boswell, James (1740-1795)
See The Journal of a Tour to the Hebrides, with Samuel Johnson, LL.D. By James Boswell, Esq. Containing Some Poetical Pieces by Dr. Johnson, relative to the Tour, and never before published; A Series of his Conversation, Literary Anecdotes, and Opinions of Men and Books: With an Authentick Account of The Distresses and Escape of the Grandson of King James II. in the Year 1746. (London: Printed by Henry Baldwin, 1785). <Link to ECCO>
Text from Johnson, Samuel and James Boswell. A Journey to the Western Islands of Scotland and The Journal of a Tour to the Hebrides, ed. Peter Levi. (New York: Penguin Books, 1984).