Peace indeed is both sweet in name and wholesome in reality; but there is all the difference in the world between peace and slavery. Peace is the calmness of freedom, slavery the worst of all evils, to be kept off at a the cost not only of war, but even of life itself.

[Et nomen pacis dulce est et ipsa res salutaris; sed inter pacem et servitutem plurimum interest. Pax est tranquilla libertas, servitus postremum malorum omnium, non modo bello sed morte etiam repellendum.]

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

Philippicae [Philippics], No. 2, ch. 44 / sec. 113 (2.113) (24 October AD 44) [tr. King (1867)]
    (Source)

(Source (Latin)). Alternate translations:

The name of peace is sweet, the thing itself is most salutary. But between peace and slavery there is a wide difference. Peace is liberty in tranquillity; slavery is the worst of all evils, -- to be repelled, if need be, not only by war, but even by death. [tr. Yonge (1903)]

And the name of peace is sweet, and the thing itself wholesome, but between peace and servitude the difference is great. Peace is tranquil liberty, servitude the last of all evils, one to be repelled, not only by war but even by death.
[tr. Ker (1926)]

The name of peace is sweet, and the thing itself is beneficial, but there is a great difference between peace and servitude. Peace is freedom in tranquility, servitude is the worst of all evils, to be resisted not only by war, but even by death.