Sir Joshua Reynolds once asked him by what means he had attained his extraordinary accuracy and flow of language. He told him, that he had early laid it down as a fixed rule to do his best on every occasion, and in every company: to impart whatever he knew in the most forcible language he could put it in; and that by constant practice, and never suffering any careless expressions to escape him, or attempting to deliver his thoughts without arranging them in the clearest manner, it became habitual to him.

James Boswell, The Life of Samuel Johnson, London, 1791, vol. 1, p. 109