Here is the quote:
Is crime consonant with nobility?
Then noblest is the crime of tyranny –
In all things else obey the laws of Heaven.
Actually, this is a quote from a quote from a quote. Suetonius says that Cicero wrote in his book Essay on Duty that Julius Caesar quoted the words from a play by Euripides entitled The Phoenician Women. A rather literate bunch, these Romans!
It appears that Caesar used the quote to justify his bid for monarchical power.