The flames kindled on the 4th of July, 1776, have spread

This is from my letter to John Adams, September 12, 1821:

I shall not die without a hope that light and liberty are on steady advance. We have seen, indeed, once within the records of history, a complete eclipse of the human mind continuing for centuries. And this, too, by swarms of the same northern barbarians, conquering and taking possession of the countries and governments of the civilized world. Should this be again attempted, should the same northern hordes, allured again by the corn, wine, and oil of the south, be able again to settle their swarms in the countries of their growth, the art of printing alone, and the vast dissemination of books, will maintain the mind where it is, and raise the conquering ruffians to the level of the conquered, instead of degrading these to that of their conquerors. And even should the cloud of barbarism and despotism again obscure the science and liberties of Europe, this country remains to preserve and restore light and liberty to them. In short, the flames kindled on the 4th of July, 1776, have spread over too much of the globe to be extinguished by the feeble engines of despotism; on the contrary, they will consume these engines and all who work them.