I . . . called on old [in his nineties] [Charles] Macklin the Comedian whom I found with a mind active and cheerful in his ninety second or third year. I could not but wonder while he related theatrical stories sixty years old . . . Here sat I forty years younger than him, listless and desponding, and unable to rid my mind of a disagreeable sensation as if I had been sitting in Edinburgh. I really my dear Temple believe that as much pain may be suffered from antipathies, as from almost any cause. Would it not torture you to be again at Professor Hunter's eating jeel. The possibility of a disturbed imagination reducing me to the mode of existence in my youth frightens me. Alas! what real advances have I made above that state! How delusive is this low-spirited thought!--But indeed I much fear that to a speculating and very feeling mind all that life affords will at times appear of no effect. When I recall the infinite variety of scenes through which I have passed, in my moment of sound sensation, I am elated; but in moments of depression, I either forget them all, or they seem indifferent.
My Life of Johnson is at last drawing to a close. I am correcting the last sheet, and have only to write an Advertisement, to make out a note of Errata and to correct a second sheet of contents, one being done. I really hope to publish it on the 25 current. My old and most intimate friend may be sure that a copy will be sent to him. I am at present in such bad spirits, that I have every fear concerning it--that I may get no profit, nay may lose--that the public may be disappointed and think that I have done it Poorly--that I may make many enemies, and even have quarrels. -- Yet perhaps the very reverse of all this may happen . . . .
-from The Essential Boswell: Selections from the Writings of James Boswell selected and edited by Peter Martin. (London: Weidenfeld & Nicolson, 2003) p. 319-320