A nation can survive its fools, and even the ambitious. But it cannot survive treason from within. For the traitor appears not a traitor — he speaks in the accents familiar to his victims, and he appeals to the baseness that lies deep in the hearts of all men. He rots the soul of a nation — he works secretly and unknown in the night to undermine the pillars of the city — he infects the body politic so that it can no longer resist. A murderer is less to be feared. The traitor is the carrier of the plague. You have unbarred the gates of Rome to him.

Marcus Tullius Cicero (106–43 BC) Roman orator, statesman, philosopher

(Spurious)

This text, widely passed around on social media, was made up for Cicero in Taylor Caldwell, A Pillar of Iron (1965).