When George Canning made a proposal to the Monroe administration (that the U.S. ally with Britain against European interference in Latin America), Monroe turned to former presidents Thomas Jefferson and James Madison for foreign policy advice.

It's pretty handy to have former presidents as buddies in times like this.

Monroe's letter to Jefferson lays out Canning's proposal, and asks Jefferson his thoughts. Specifically, Monroe asks three questions about the situation and the potential significance of agreeing or not agreeing to the alliance. He's trying to figure out whether agreeing would get the U.S. involved in European affairs, and he wonders if Britain shouldn't make a firm decision about where they stand: with European monarchies or the freedom of the Americas. (Source)

The letter shows us Monroe's internal debate when presented with the potential British alliance. In combination with Jefferson's response, you can see the seeds of ideas presented in the Monroe Doctrine being discussed. Ooh, foreshadowing…