England's southern colonies in North America developed a farm economy that could not survive without slave labor. Many slaves lived on large farms called plantations. These plantations produced important crops traded by the colony, crops such as cotton and tobacco.
And
Throughout the 17th and 18th centuries people were kidnapped from the continent of Africa, forced into slavery in the American colonies and exploited to work as indentured servants and labor in the production of crops such as tobacco and cotton.
Fevers, chills, headaches, fatigues.
Because a larger majority of the colonists were loyal to Britain (Federalists) Jefferson was trying to convince them that their original purpose of starting a new country was to be completely independent, so that is his purpose.