The actual quotation:
"It seems to be the law of our general nature, in spite of individual exceptions; and experience declares that man is the only animal which devours his own kind, for I can apply no milder term to the governments of Europe, and to the general prey of the rich on the poor."
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Monticello historic foundation maintains a webpage of "spurious Jefferson quotations" which serves, generally, as a caution to us all. http://www.monticello.org/site/jefferson/spurious-quotations