Thomas Jefferson to Richard Gem

Volume 15: 27 March 1789 to 30 November 1789
(Princeton University Press, 1958), 398-9
[Paris, 9 Sep. 1789]

Th:J. to Doctor Gem 

The hurry in which I wrote my letter to Mr. Madison, which is in your hands, occasioned an inattention to the difference between generations succeeding each other at fixed epochs, and generations renewed daily and hourly. It is true that in the former case the generation, when at 21. years of age, may contract a debt for 34. years, because a majority of them will live so long. But a generation consisting of all ages, and which legislates by all it's members above the age of 21. years, cannot contract for so long a time, because their majority will be dead much sooner. Buffon gives us a table of 23,994 deaths, stating the ages at which they happened. To draw from these the result I have occasion for, I suppose a society in which 23,994 persons are born every year and live to the ages stated in Buffon's table. Then the following inferences may be drawn. Such a society will consist constantly of 617,703 persons of all ages. Of those living at any one instant of time, one half will be dead in 24 years 8 months. In such a society, 18,675 will arrive every year at the age of 21. years complete. It will constantly have 348,417 persons of all ages above 21 years and the half of those of 21. years and upwards living at any one instant of time will be dead in 18 years 8. months, or say 19. years. Then the contracts, constitutions, and laws of every such society become void in 19. years from their date.

PrC (DLC); recorded in SJL as written on 9 Sep. 1789.