Nation is its citizens and Jefferson stresses basically that that is why the people must participate in the government. The government is of the people for the people which means that the government is made up from the citizens of the United States. It is those same citizens that, by their right to vote, choose who will do their will in the government. Precisely because the people choose who will be in the government is the reason why they must be more active as it will decide what policies were going to be pushed.
What happened right after the Revolutionary War ended? It's easy to think the United States of America was birthed immediately after the British surrendered at Yorktown, but in truth it was a long, arduous process to transform the idealistic embryonic state to a fully-formed nation. It actually took several years of difficult diplomacy after the last British soldier surrendered for a peace treaty with Great Britain to be established. Not even the most insanely cool Revolutionary War hero could help speed up the process. It also took a long time for the British soldiers to actually leave American soil, taking loyalists and slaves with them back to England.
The real work began after the British left, however. History rarely plays out easily for anyone. With much toil and debate, the United States constitution was written after the country spent years languishing in economic hardship. Rebellions, disorganized states, and an ineffective Continental Congress threatened to destroy the great experiment that was America. Luckily, the country managed to get its act together and write the constitution we're still using today. However, it was certainly a winding, complicated road to get there.
