Titus Livius (Livy), The History of Rome, Book 5
Benjamin Oliver Foster, Ph.D., Ed.

39. The very Gauls themselves, stunned by¹ the marvellous victory they had so suddenly gained, at first stood rooted to the spot with amazement, like men that knew not what had happened; then they feared an ambush; after that they fell to collecting the spoils of the slain and erecting piles of arms, as their custom is; then at last having discovered no hostile movement anywhere, they began their march, and a little before sunset reached the environs of Rome. [2] There, when the cavalry had reconnoitred and had reported that the gates were not closed, that no out-guards were watching before the gates, that no armed men were on the walls, astonishment held them spell-bound as before; [3] and fearful of the night and the lie of the unknown : City, they went into camp between Rome and the Anio, after sending off patrols about the walls and the rest of the gates, to find out what the enemy in their desperate case could possibly be at. [4] As for the Romans, inasmuch as more, on escaping from the battle, had fled to Veii than to Rome, and no one supposed that any were left alive except those who had found refuge in the City, they mourned for all alike, both the living and the dead, and well nigh filled the City with lamentation. [5] But presently their personal griefs were overwhelmed in a general panic, with the announcement that the enemy was at hand; and soon they could hear the dissonant howls and songs of the barbarians, as their squadrons roamed about the walls. [6] During all the time that intervened before the following morning their hearts were. in, such. suspense, that each moment they anticipated an immediate attack:. on the first arrival of the enemy, because they had come close to the [p. 135]City —for they would have stopped at the Allia, had² this not been their design; —again, [7] towards sundown, because there was little daylight left, they thought that they would enter the City before nightfall; then they concluded that they had put it off till night, to strike more fear into them. [8] Finally the approach of dawn put them beside themselves, and close upon these restless apprehensions came the evil they were dreading, when the hostile forces entered the city gates. Yet neither that night nor the following day did the citizens at all resemble those who had fled in such consternation at the Allia. [9] For having no hopes that they could protect the City with so small a force as remained to them, they resolved that the men of military age and the able-bodied senators should retire into the Citadel and the Capitol, with their wives and children; [10] and, having laid in arms and provisions, should from that stronghold defend the gods, the men, and the name of Rome; [11] that the flamen and the priestesses of Vesta should remove the sacred objects pertaining to the State far from the bloodshed and the flames, nor should their cult be abandoned till none should be left to cherish it. [12] If the Citadel and the Capitol, where dwelt the gods; if the senate, the source of public wisdom; if the young men capable of bearing arms survived the impending destruction of the City, they could easily bear to lose the crowd of old men left behind them, who were bound to die in any case. [13] And in order that the multitude of commoners might endure it with the more composure, the old men who had triumphed and those who had been consuls declared publicly that they would perish with those others, nor burden with bodies [p. 137]incapable of bearing arms in defence of the country³ the scanty stores of the fighting men.