Reflection must be reserved for solitary hours; whenever she was alone, she gave way to it as the greatest relief; and not a day went by without a solitary walk, in which she might indulge in all the delight of unpleasant recollections.

– Jane Austen

Pride and Prejudice, Chapter 37. While Elizabeth is generally a social person with a gift for witty conversation, during her last days at Hunsford and Rosings likes to go on solitary walks and reflect. She keeps thinking about the letter Darcy gave her.