What subject did Jefferson find to be the most interesting?

Jefferson was a Renaissance man. He was interested in everything. His home had a museum, he catalogued all the plants in Virginia, he was an inventor, he was an avid reader and gave 6,000 books to start the Library of Congress. He designed his home and gave suggestions on Washington DC. He was a plantation owner, the father of 6 children from his slave Sally Hemming, he believed in small government and wrote books on government.