Argument of Tyrants, Creed of Slaves

I like the following quote, which I think is attributed to William Pitt the Younger:

"Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves."

He made this statement in a speech in the British House of Commons, in 1783. William might have been against the American Revolution, and for monarchy, but, anyway....