origin of the fourth estate

Where the term Fourth Estate comes from:

The idea of the press as a "Fourth Estate" came to prominence during the nineteenth century. In 1837 Robert Carlyle referred to "A Fourth Estate of Noble Editors" in The French Revolution: A History, and in On Heroes and Hero Worship (1841) stated that "Burke said there were Three Estates in parliament; but in the Reporters' Gallery yonder, there sat a Fourth Estate more important far than they all". Carlyle continued: "Literature is our Parliament too. Printing, which comes necessarily out of Writing, I say often, is equivalent to Democracy. Invent Writing, Democracy is inevitable."