The historian Josephus reports many supernatural signs and portents that were given to the inhabitants of Jerusalem shortly before its destruction. Let us briefly examine the more prominent ones.1
There was a star resembling a sword that stood over the city, and a comet, that continued a whole year. Another time, in the middle of the night, a light shone around the altar and Temple, making it appear to be bright daytime, which lasted for half an hour.
One night, the eastern gate of the Temple, that normally took twenty men to shut with difficulty, opened of its own accord. Another time, at the feast of Pentecost, the priests felt a great quaking, heard a great noise, and then they heard a sound as of a great crowd, saying, “Let us remove hence.”
Four years before the war began, a man went around Jerusalem saying nothing else but, “A voice from the east, a voice from the west, a voice from the four winds, a voice against Jerusalem and the holy house, a voice against the bridegrooms and the brides, and a voice against this whole people!” And, “woe, woe to Jerusalem!” He did this for seven years and five months, until he was killed by a stone from one of the Roman siege weapons.
Josephus also reports, and speaks of eyewitness testimony confirming it, that there was an evening while the city was still at peace with the Romans, in which before sunset, chariots and troops of soldiers in their armor were seen running about among the clouds, and surrounding cities.
Now, it was obvious to Josephus, and should be obvious to us, that these were given to your ancestors, as portents of the dangers they were about to face. Some of the signs may also have been the direct fulfillment of prophecies, such as these words in Isaiah: “A sound of tumult from the city, a sound from the Temple, a sound of YHWH paying retribution to his enemies.” 2
And some of them may have had specific meanings. For example, the light around the altar, the sound heard by the priests, and the eastern gate opening of its own accord, may have been the departure of YHWH's glory cloud3 from the second Temple, similar to how it left the first Temple; although some of your teachers say it was never in the second Temple to begin with, in which case, they were perhaps signs representing its departure symbolically.
And the sight of troops in the clouds resembled a vision given to the prophet Joel concerning a “day of YHWH,” a “day of darkness and gloom, a day of clouds and thick fog,” in which he saw horses and the sound of chariots, a mighty army scaling walls and rushing into a city.4
YHWH foretold such supernatural events through the mouth of Joel, when he said: “I will give wonders in the heavens, and in the earth, blood and fire, and pillars of smoke. The sun will be turned into darkness, and the moon into blood, before the coming of the great and terrifying day of YHWH.”
But deliverance was also promised for those calling on YHWH. For Joel said: “And it will be, that everyone who will call on the name of YHWH will escape; for in Mount Zion and in Jerusalem will be deliverance, as YHWH has said, and in the survivors whom YHWH calls.” 5
Now, Joel’s prophecy may really be referring to events beyond the destruction of Jerusalem by the Romans, because it says that deliverance would be “in Mount Zion,” “in Jerusalem” and “in the survivors.” But the signs and portents that were seen in the days of the Romans match up closely enough, as if to remind those paying attention that this was a “day of YHWH,” even if it was not a complete fulfillment of the prophecy.
In the days of the Romans, there was really only one way to escape the things to come upon Jerusalem, and that was to leave the city when it became clear that war was coming. But the people would have been trapped inside when Cestius, who was president of the Roman province of Syria,6 brought some of the Roman army into the city, and they were ready to set fire to the gate of the Temple.
At that time, Cestius could have taken Jerusalem easily; but then, according to Josephus, he retreated from the city “without any reason in the world.” 7 The seditious among your ancestors ran after him and killed many of his soldiers.
Josephus says: “After this calamity had befallen Cestius, many of the most eminent of the Jews swam away from the city, as from a ship when it was going to sink.” 8
This was the only safe opportunity to leave Jerusalem before the calamities fell upon it, for soon after this, the seditious returned and made preparations for war against the Romans.