|Louisa Grenville as a child|
Louisa Stanhope (1758-1829), the second wife of Charles, the 3rd Earl of Stanhope, was fond of quoting from passages in the books and poems she had read. She was the only daughter of Margaret Eleanor Grenville (neé Banks) and Henry Grenville, and the first cousin of William Pitt the younger on his mother's side of the family. In a previous post I wrote about number 13 Bath Crescent, Louisa's home with her parents, and I spoke of her close friendship with Pitt's sister Lady Harriot. Alongside William Pitt, Louisa was also a witness at Lady Harriot and Edward Eliot's marriage ceremony in 1785.
An online genealogy site claims that Louisa was born on August 10, 1758 at Wotton Underwood in Buckinghamshire.  The site does not give a source for this information, and it seems to be contested by Louisa herself. Amongst her papers from later life, she personally wrote that she "was born the Twenty Eighth of July 1758 in Saville Row London.”  I personally give credit to Louisa's own words about the basic facts of her birth. In March 1781, Louisa married Charles Stanhope. It was then just eight months after the death of Charles Stanhope's first wife, Pitt's eldest sister Lady Hester Mahon. It was not a happy marriage, but Louisa did bear Charles Stanhope three sons.
Amongst her papers are a collection of quotes and scribblings in her own handwriting on various sizes of paper. The majority of these are without date, but it is clear that they span a long period of time. I'm sharing them on this site as they offer a fascinating insight into the life and interests of a relatively unknown Georgian aristocratic lady who was a cousin of Pitt.
Below are a sample of a few quotes in her collection:
“Write injuries in dust, but kindness in Marble”
“Possession always falls short of Expectation”
“Wealth cannot purchase, or Fashion bestow, real Happiness”
“That is the best & most valuable kind of knowledge that is most subservient to the best ends, which tends to make a man wiser and better and more agreeable and useful both to himself and Others. For Knowledge is but a means that rebates[?] to some end & as all means are to be judg’d by the excellency of ye end & thrive expediency to produce it so that must be the best knowledge that hath the directest tendency to promote the best ends and Man’s own true happiness & that of others, in which the glory of God. The ultimate end is ever necessarily comprised.” - on Self-Knowledge
“Let recollection call to view the past, and steady prudence weigh the present actions.”
“It is in the Storm that men must firmly grasp the Cloak that wraps them whatever its shape”
Sophocles - “For O! to be unhappy and know ourselves alone the guilty cause of all our Sorrows, is the worst of Woes.” 
Louisa, by then the Dowager Countess Stanhope, died on March 7, 1829 at the age of 70 . Her death was reported in the Morning Journal, Morning Post, Morning Chronicle, Times, and Courier. One of the newspaper pieces quoted the following brief obituary: “Died on Saturday at her House in Clarges Street after a lingering illness the Dowager Countess Stanhope." 
As a postscript, the last surviving member of the Pitt family, William's older brother John, the 2nd Earl of Chatham, wrote to Philip Henry, the 4th Lord Stanhope (1781-1855), on March 10, 1829 to express his sincere condolences on the death of Stanhope's mother.  The Dowager Countess Stanhope was Lord Chatham's maternal cousin, and he admitted that he was aware the illness had been of some duration.  At this point in time, Lord Chatham was 72 years old, and writing from Brighton. He was, by far, the sole surviving member of the Pitt family. Five years later, in September 1835, he passed away with no children, and the Earldom of Chatham became extinct.
2.Memoranda respecting the Birth & Death of Louisa Dowager Countess Stanhope & Memoranda in her hand writing respecting the Banks & Grenville Families. The Kent History and Library Centre. The Stanhope of Chevening Manuscripts: U1590/C118.
3. Verses, Extracts &tc in the handwriting of Louisa Dowager Countess of Stanhope and found amongst her Papers. The Kent History and Library Centre, The Stanhope of Chevening Manuscripts: U1590/C114.
4. Memoranda respecting the Birth & Death of Louisa Dowager Countess Stanhope & Memoranda in her hand writing respecting the Banks & Grenville Families. The Kent History and Library Centre. The Stanhope of Chevening Manuscripts: U1590/C118.
6. John, 2nd Earl of Chatham, to Lord Stanhope, March 10, 1829. Memoranda respecting the Birth & Death of Louisa Dowager Countess Stanhope & Memoranda in her hand writing respecting the Banks & Grenville Families. The Kent History and Library Centre. The Stanhope of Chevening Manuscripts: U1590/C118.
Louisa, Countess of Stanhope (neé Grenville) as a child. Image Source