Known as "The Diary of Thomas Thistlewood", Thistlewood's 14,000-page diary provides a detailed record of his life and deep insight into plantation life from agricultural techniques to slave–owner relations. Thistlewood was self-educated and a prolific reader for his time and even more so in British colonial society. He often practiced medicine on his slaves, though some of his practices, like those of European doctors in Jamaica, were questionable. He was also knowledgeable in botany and horticulture. He bought and read a number of books about religion, husbandry, and estate management, and he watched and marvelled at the appearance of Halley's Comet in 1759.