Answer:
... intelligent enough to continue to be united.
Explanation:
John Jay was one of the Founding Fathers of the U.S. He was in favor of a strong, centralized government. In this excerpt Jay makes the indirect statement people of any country (if, like the Americans, intelligent and well informed) that Americans can be considered as mentioned above.
Then he states that Americans, being intelligent and well informed, will continue to unite themselves under one federal government.