Titus Livius (Livy), The History of Rome, Book 1
Benjamin Oliver Foster, Ph.D., Ed.

31. After the defeat of the Sabines, when¹ King Tullus and the entire Roman state were at a high pitch of glory and prosperity, it was reported to the king and senators that there had been a rain of stones on the Alban Mount. [2] As this could scarce be credited, envoys were dispatched to examine the prodigy, and in their sight there fell from the sky, like hail-stones which the wind piles in drifts upon the ground, a shower of pebbles. [3] They thought too that they heard a mighty voice issuing from the grove on the mountain-top, which commanded the Albans to celebrate, according to the fashion of their fathers, the sacrifices, which as though they had forsaken their gods along with their city, they had given over to oblivion, either adopting Roman rites, or in anger at their fortune, such as men sometimes feel, abandoning the worship of the gods. [4] The Romans also, in consequence of the same portent, undertook an official nine days' celebration, whether so commanded by the divine utterance from the Alban Mount —for this too is handed down —or on the advice of soothsayers. [5] At all events it remained a regular custom that whenever the same prodigy was reported there should be a nine days' observance.

Not very long after this Rome was afflicted with a pestilence. This caused a reluctance to bear arms, yet no respite from service was allowed by the warlike king (who believed, besides, that the young men were healthier in the field than at home) until he himself contracted a lingering illness. [6] Then that haughty spirit was so broken, with the breaking of his health, that he who had hitherto thought nothing less worthy of a king than to devote his mind to sacred rites, suddenly became a prey to all sorts of [p. 113]superstitions great and small, and filled even the² minds of the people with religious scruples. [7] Men were now agreed in wishing to recall the conditions which had obtained under King Numa, believing that the only remedy left for their ailing bodies was to procure peace and forgiveness from the gods. [8] The king himself, so tradition tells, in turning over the commentaries of Numa discovered there certain occult sacrifices performed in honour of Jupiter Elicius, and devoted himself in secret to those rites; but the ceremony was improperly undertaken or performed, and not only was no divine manifestation vouchsafed him, but in consequence of the wrath of Jupiter, who was provoked by his faulty observance, he was struck by a thunderbolt and consumed in the flames of his house. Tullus was greatly renowned in war and reigned thirty-two years.