If you spend any time in the Jane Austen community, especially online, you will see many Janeite's talk about "The Jane Austen Letters". This blog talks about what the Letters were, to whom they were written, and the mysterious circumstances surrounding their destruction.
What are the Jane Austen Letters?
When avid Jane Austen fans reference "the letters", they are almost always talking about the letters between Jane Austen and her sister Cassandra Austen.
Who was Cassandra Austen?
Cassandra Austen was the sixth child of Rev. Austen and Mrs. Austen. Cassandra was born on January 9th, 1773. Cassandra was Jane Austen's only sister. Cassandra was older than Jane by only two years, and their brother Francis was born in between them. Yes, Mrs. Austen gave birth once a year for three years in a row! As an adult, Cassandra studied art, and made artwork for Jane's manuscript "The History of England". Cassandra created two paintings depicting her sister, a painting of Jane from behind (see below) and a never-finished sketch. If you're a Jane Austen fan, you've seen it. Like Jane, Cassandra never married. She was engaged to Thomas Fowle, who died in the Caribbean, leaving Cassandra 1000 pounds. (I tried researching how much 1000 pounds would be today and got drastically different answers from different inflation calculators) Cassandra passed away in 1845, at age 72. Before she passed away, she destroyed 2/3 of the letters Jane wrote to her. (More on that later)
What are in these letters?
The letters between Jane and Cassandra discuss a variety of subjects, including their family members, historical events, and even information about Jane's novels. In one letter, Jane tells Cassandra that she is almost done with Sense and Sensibility, which she refers to as S&S in the letter, and that their brother is going to a publisher soon.
Why are these letters important?
These letters are important to scholars and fans alike, because they give an insight and a timeline of Jane Austen's life. They also serve as enlightenment to historical accuracy and current events. While the letters that survived don't have anything too salacious, (we can assume that any letter with salacious content was destroyed) they still give us insight to Jane's views of people, balls, current events, etc.
What happened to these letters?
Cassandra outlived her sister by 26 years and would read her sisters letters for comfort after Jane died. Towards the end of her life, Cassandra burned approximately 2/3 of Jane's letters. (1843) There are many theories why Cassandra would have burned some of her sister's letters but not all. Was there sensitive material in the letters that the Austen's wouldn't want anyone knowing? Its more realistic that it was just a formality, as it was actually common practice to destroy letters in that era. 160 letters from Jane Austen have survived, 95 of them were sent to Cassandra.
Where can I read these letters?
There are many places online where you can read transcripts of the letters. My personal favorite place is here, The Princeton University blog.