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This quote is from an 1818 letter by John Adams. In it, Adams is suggesting that the American Revolution was made possible by the awakening of an American consciousness that made most people in the colonies feel different from the British. Americans no longer wanted to think of themselves as royal subjects, Adams is saying, but instead embraced republican principles of liberty, equality, and independence.

Adams is not talking about any particular British policy that may have sparked the war, such as the Intolerable Acts. He is talking more broadly and historically and suggesting that American separation from Britain may have been inevitable because history, philosophy, and interests were making them a separate people.

(This clashes with other quotes that Adams said or wrote earlier in his life. For example, he also said he thought that only one-third of the colonial population supported independence, one-third were generally loyal to Britain, and one-third didn't care or preferred to be neutral. Hardly a match for his claim in the 1818 letter that a new radical spirit had sweep the minds and hearts of all Americans.)