"This is a strong confirmation of the truth of a remark of his, which I have had occasion to quote elsewhere 5, that 'a man may write at any time, if he will set himself doggedly to it;' for, notwithstanding his constitutional indolence, his depression of spirits, and his labour in carrying on his Dictionary, he answered the stated calls of the press twice a week from the stores of his mind, during all that time having received no assistance, except four billets in No. 10 by Miss Mulso, now Mrs. Chapone; No. 30, by Mrs. Catharine Talbot; No. 97, by Mr. Samuel Richardson, whom he describes in an introductory note as 'An authour who has enlarged the knowledge of human nature, and taught the passions to move at the command of virtue;' and Numbers 44 and 100, by Mrs. Elizabeth Carter."
— Boswell, James (1740-1795)
(I, p. 109; p. 113 in Penguin)
See The Life of Samuel Johnson, LL.D. Comprehending an Account of His Studies and Numerous Works, in Chronological Order; a Series of His Epistolary Correspondence and Conversations With Many Eminent Persons; and Various Original Pieces of His Composition, Never Before Published. The Whole Exhibiting a View of Literature and Literary Men in Great-Britain, for Near Half a Century, During Which He Flourished. In Two Volumes. By James Boswell, Esq. 2 vols. (London: Printed by Henry Baldwin, for Charles Dilly, in the Poultry, 1791). <Link to ESTC><Vol. I in ECCO-TCP><Vol. II>
My main reading text is James Boswell, The Life of Johnson, ed. Claude Rawson, (New York: Knopf, 1992). Also reading in David Womersley's Penguin edition, 2008.
First edition in Google Books, <Vol. I><Vol. II>. See also Jack Lynch's online e-text, prepared from the 1904 Oxford edition <Link>.