I think a person's books can tell more about them than almost anything else in their household. Saturday I went to an estate sale in search of books to sell.
The ad promised "1000s of books". There wasn't even 1000 but there were a great many. I find that estate sale givers always overestimate the number of books.
The former owner was a life time member of Weight Watchers, a Methodist, a diabetic and had a superficial interest in architecture, decorating and drawing. She was very fond of anything published by Rodale Press (a notorious publisher of penny books) , dabbled in natural healing and did a bit of travel, all of it domestic. At one time she'd practiced law and officed out of her home. Given the number of "how to succeed as a solo lawyer" books she wasn't very successful.
She also spent more time at Half Price Books than I do, which meant the bulk of her books were worthless on the resale market. Oh well. I did find a few gems but some days are like that.
Even in Australia.