They were written fast, anonymously, and for a newspaper fight. Today they are the closest thing America has to an owner's manual for the Constitution, quoted by the Supreme Court to this day.
The Federalist Papers are 85 essays published in 1787 and 1788 to persuade New Yorkers to ratify the Constitution. They explain and defend the proposed government clause by clause, and they remain the single most authoritative guide to what the framers intended.
They were written by three men under one shared pen name, Publius: Alexander Hamilton, who organized the project and wrote the most; James Madison, who wrote the most enduring; and John Jay, who wrote only a few before falling ill.
They were journalism, not scripture. Cranked out rapidly to meet the ratification deadline, printed in newspapers, aimed at swaying a close political vote in a single pivotal state. Their lasting authority was earned later, not assumed.
And they have lasted extraordinarily. Courts, including the Supreme Court, cite the Federalist Papers as a window into the original meaning of the Constitution. No. 10 on faction and No. 51 on checks and balances are among the most studied political essays ever written.