He advised me to keep a journal of my life, fair and undisguised. He said it would be a very good exercise, and would yield me infinite satisfaction when the ideas were faded from my remembrance. I told him that I had done so ever since I left Scotland. He said he was very happy that I pursued so good a plan. And now, O my journal! art thou not highly dignified? Shalt though not flourish tenfold? No former solicitations or censures could tempt me to lay thee aside; and now is there any argument which can outweigh the sanction of Mr. Samuel Johnson? He said indeed that I should keep it private, and that I might surely have a friend who would burn it in case of my death. For my own part, I have at present such an affection for this my journal that it shocks me to think of burning it. I rather encourage the idea of having it carefully laid up among the archives of Auchinleck. However, I cannot judge fairly of it now. Some years hence I may. I told Mr. Johnson that I put down all sorts of little incidents in it. "Sir," said he, "there is nothing too little for so little a creature as man. It is by studying little things that we attain the great knowledge of having as little misery and as much happiness as possible." [16 July 1763]
Boswell's London Journal