James Boswell, Life of Johnson
(aetat. 64, 1773):
On Friday, May 7, I breakfasted with him at Mr. Thrale's in the Borough. While we were alone, I endeavoured as well as I could to apologise for a lady who had been divorced from her husband by act of Parliament. I said, that he had used her very ill, had behaved brutally to her, and that she could not continue to live with him without having her delicacy contaminated; that all affection for him was thus destroyed; that the essence of conjugal union being gone, there remained only a cold form, a mere civil obligation; that she was in the prime of life, with qualities to produce happiness; that these ought not to be lost; and, that the gentleman on whose account she was divorced had gained her heart while thus unhappily situated. Seduced, perhaps, by the charms of the lady in question, I thus attempted to palliate what I was sensible could not be justified; for when I had finished my harangue, my venerable friend gave me a proper check: 'My dear Sir, never accustom your mind to mingle virtue and vice. The woman's a whore, and there's an end on't.'
The woman was Lady Diana Spencer (1734-1808), the husband was Sir Frederick St. John, 2nd Viscount Bolingbroke, and the gentleman on whose account she was divorced was Johnson's friend Topham Beauclerk.