The following quotation is often attributed to Thomas Jefferson:
By making this wine vine known to the public, I have rendered my country as great a service as if I had enabled it to pay back the national debt.
This statement has never been found in Jefferson's writings. Its true source is most likely John Adlum, who corresponded extensively with Jefferson on the subject of wine.1 Adlum is quoted by a friend as saying, "In bringing this grape into public notice, I have rendered my country a greater service, than I would have done, had I paid the national debt."2 Adlum was speaking of the Catawba grape.
1. See, e.g., Jefferson to Adlum, October 7, 1809, in PTJ:RS, 1:586-87. Transcription available at Founders Online. Transcriptions of additional correspondence between Jefferson and Adlum are also available at Founders Online.