A Self-Fulfilling Prophecy

In Poul Anderson's "The Virgin of Valkarion," it had been prophesied that, when the Thirty Ninth Dynasty ends at an eclipse of the Two Moons, a heathen will arrive, overthrow both church and state, Temple and Imperium, and found the glorious Fortieth Dynasty.

Thus, when the old Emperor is dying without an heir and as the eclipse is approaching, Temple priests order their slaves to kill a barbarian approaching the city and the young Empress orders a captain of the guard at the city gate to direct an approaching barbarian to a particular inn where she will await him.

Sure enough, a barbarian seeking employment arrives, has to defend himself against the Temple slaves and then has no choice but to lead the fight to prevent a Temple theocracy after the death of the Emperor. Then, with both Emperor and High Priest dead and with both Temple and Palace destroyed, the barbarian becomes the new ruler, marrying the widowed Empress. But, if no prophecy had been made, then no Temple slaves would have tried to kill him, the Empress would have made no preparations to receive him and he would either have found employment in the city or continued his wanderings.

So did the prophetess know that her prophecy would cause the prophesied events?