That is a great quote, one that somehow I missed over the years of watching the old Claudius programs. I finally found the whole thing:

The frog-pool wanted a king.
Jove sent them Old King Log.
I have been as deaf and blind and wooden as a log.
The frog-pool wanted a king.
Let Jove now send them Young King Stork.
Caligula's chief fault: his stork-reign was too brief.
My chief fault: I have been far too benevolent.
I repaired the ruin my predecessors spread.
I reconciled Rome and the world to monarchy again.
Rome is fated to bow to another Caesar.
Let him be mad, bloody, capricious, wasteful, lustful.
King Stork shall prove again the nature of kings.
By dulling the blade of tyranny I fell into great error.
By whetting the same blade I might redeem that error.
Violent disorders call for violent remedies.
Yet I am, I must remember, Old King Log.
I shall float inertly in the stagnant pool.
Let all the poisons that lurk in the mud hatch out.