Here’s another one (though actually I’ve quoted it before):
A cause whose nature is not directly perceptible can be discovered through the effect which invariably accompanies it. What is an absolute monarch? He is one at whose command war at once begins when he says it shall do so. And conversely, what is a limited monarch? He is one who must first ask the people whether or not there is to be a war, and if the people say that there shall be no war, then there will be none. For war is a condition in which all the powers of the state must be at the head of state’s disposal.Now the monarch of Great Britain has waged numerous wars without asking the people’s consent. This king is therefore an absolute monarch, although he should not be so according to the constitution. But he can always bypass the latter, since he can always be assured, by controlling the various powers of the state, that the people’s representatives will agree with him; for he has the authority to award all offices and dignities. This corrupt system, however, must naturally be given no publicity if it is to succeed. It therefore remains under a very transparent veil of secrecy.
That’s from The Contest of Faculties. Do note, though, that a few pages earlier (and also in a footnote) Kant warned that “a people which has a monarchic constitution” cannot “claim the right to alter it, or even nurse a secret desire to do so” (my emphasis).