The message of Monroe was an assertion that the fate of both the Americas was of immediate concern to the safety of the United States, because the fate of its sister republics intimately affected its own security.

This proved to be an enduring definition of policy, because for many years there was a real institutional difference between the American hemisphere and the rest of the world and because oceanic boundaries were the most substantial that the world affords.
Adams, however, would have been the last to claim that his method of securing the fundamental purposes of the United States was itself fundamental.

It is particularly important for Americans to make a distinction between the things which they have always wished to obtain and the methods which they have from time to time used.

To build a policy today on the alleged isolation of the American continents would be almost as absurd as to try to build a government on the belief in Divine Right.

The American continents are no longer separated from the rest of the world by their national institutions, because the spirit of these institutions has permeated much of Europe, Asia, and even Africa.
No boundaries, not even oceans, can today prohibit international interference.