Extract from Thomas Jefferson’s Memoir on the Megalonyx

In fine, the bones exist: therefore the animal has existed. The movements of nature are in a never ending circle. The animal species which has once been put into a train of motion, is still probably moving in that train. For if one link in nature's chain might be lost, another and another might be lost, till this whole system of things should evanish by piece-meal; a conclusion not warranted by the local disappearance of one or two species of animals, and opposed by the thousands and thousands of instances of the renovating power constantly exercised by nature for the reproduction of all her subjects, animal, vegetable, and mineral. If this animal then has once existed, it is probable on this general view of the movements of nature that he still exists, and rendered still more probable by1 the relations of honest men applicable to him and to him alone. It would indeed be but conformable to the ordinary economy of nature to conjecture that she had opposed sufficient barriers to the too great multiplication of so powerful a destroyer. If lions and tygers multiplied as rabbits do, or eagles as pigeons,2 all other animal nature would have been long ago destroyed, and themselves would have ultimately extinguished after eating out their pasture.

Published in Transactions of the American Philosophical Society 4 (1799), 246–60, esp. 255–6, which was based on a missing fair copy and includes a dateline of 10 Feb. 1797 for the portion of the letter extracted above and a 10 Mar. 1797 postscript.
1In place of text from “For if one link” to this point, TJ’s undated Dft (DLC:TJ Papers, 233:41752–7) reads “and if he be still in being, there is no reason to disbelieve.”
2Preceding four words not in Dft.
Date Range
February 10, 1797