It's a fact as immutable as the Third Law of Sod that there is no such thing as a good Grand Vizier. A… — Terry Pratchett

It's a fact as immutable as the Third Law of Sod that there is no such thing as a good Grand Vizier. A predilection to cackle and plot is apparently part of the job spec.

p. 144Source: Wikiquote · CC BY-SA 4.0