Monticello, May 14, 1806

Sir, I have received a copy of the evidence at large respecting the discovery of the vaccine inoculation which you have been pleased to send me, and/or which I return you my thanks. Having been among the early converts, in this part of the. globe, to its efficiency, I avail myself of this occasion of rendering you a portion of the tribute of gratitude due to you from the whole human family. Medicine has never before produced any single improvement of such utility. Harvey's discovery of the circulation of the blood was a beautiful addition to our knowledge of the animal economy, but on a review of the practice of medicine before and since that epoch, I do not see any great amelioration which has been derived from that discovery. You have erased from the calendar of human afflictions one...