Jeffeson wrote extensively about this topic, at least indirectly. Certainly he hoped that a government based on self-rule and essential liberties would be able to persist. But he also believed that changes would occur, even revolutionary changes, and that this might be a good thing. In response to Shays' Rebellion in 1787, for example, he wrote James Madison that "a little revolution...was a good thing, and as necessary in the political world as storms in the physical." Later that year, with Madison immersed in the debates at the Constitutional Convention in Philadelphia, Jefferson wrote that "the earth belongs...to the living," suggesting that no generation had the authority under natural law to bind future generations to any legal, political, or fiscal obligation. The revolutionary implications of this statement are fairly obvious. Jefferson was also committed to the territorial expansion of the United States, a process he did much to advance with the Louisiana Purchase, and he was more than aware that westward expansion would alter the political landscape. Late in his life, in fact, he wrote with disillusionment about the possibility that the American government would persist as he and the rest of his generation had established it. Responding to the Missouri crisis and compromise, he claimed that limits placed on the expansion of slavery would eventually lead to the downfall of the nation. So throughout his life, Jefferson thought that change, for better or for worse, would be the lot of the American government. It is perhaps too simple to, as many politicians and pundits are wont to do, ask what Jefferson would make of one political policy or another, but certainly many of his writings demonstrate that he envisioned, and at times embraced, fundamental changes to the United States.