M. Tullius Cicero, On the Consular Provinces
C. D. Yonge, Ed.

Nature had previously protected Italy by the Alps, not without some especial kindness of the gods in providing us with such a bulwark. For if that road had been open to the savage disposition and vast numbers of the Gauls, this city would never have been the home and chosen seat of the empire of the world. Now, indeed, they are at liberty to sink down if they please; for there is nothing beyond those lofty heights as far as the ocean itself, which can be any object of fear to Italy. But still it will be the work of one or two summers finally to bind the whole of Gaul in everlasting chains either by fear, or hope, or punishment or reward, or arms, or laws. And if our affairs there are left in an unfinished state, and while there is still some bitterness of feeling remaining, although the enemy may be pruned back severely for the present, still they will raise their heads again some time or other, and come forth with recruited strength to renew the war.