What was Thomas Jefferson greatest accomplishments?

After Thomas Jefferson died, a member of his family found instructions that Jefferson had left as to what should be placed on his tombstone. Jefferson considered these three accomplishments the most important to him, and he hoped he would be remembered for them.

HERE WAS BURIED THOMAS JEFFERSON AUTHOR OF THE DECLARATION OF AMERICAN INDEPENDENCE OF THE STATUTE OF VIRGINIA FOR RELIGIOUS FREEDOM AND FATHER OF THE UNIVERSITY OF VIRGINIA

Jefferson, of course, accomplished much more during his lifetime. He served as colonial and state representative and governor of Virginia; held various public offices, including ambassador and Secretary of State, Vice President, and 3rd President of the United States. He was also instrumental in obtaining the Louisiana Territory for the United States, which doubled the size of the nation, and getting Congress to appropriate funds for the Lewis and Clark Expedition. He was also a noted scientist and inventor and agriculturalist.