comet in these terms:
"Here thou art again, thou cause of the tears of many mothers! It is
long since I have seen thee, but I see thee now, more terrible than
ever; thou threatenest my country with complete ruin!"

In 1455, the same comet made a more memorable appearance still. The
Turks and Christians were at war, the West and the East seemed armed
from head to foot--on the point of annihilating each other. The
crusade undertaken by Pope Calixtus III. against the invading
Saracens, was waged with redoubled ardor on the sudden appearance of
the star with the flaming tail. Mahomet II. took Constantinople by
storm, and raised the siege of Belgrade. But the Pope having put aside
both the curse of the comet, and the abominable designs of the
Mussulmans, the Christians gained the battle, and vanquished their
enemies in a bloody fight. The _Angelus_ to the sound of bells dates
from these ordinances of Calixtus III. referring to the comet.

In his poem on astronomy, Daru, of the French Academy, describes this
episode in eloquent terms:

"Un autre Mahomet a-t-il d'un bras puissant
Aux murs de Constantine arbore le croissant:
Le Danube etonne se trouble au bruit des armes,
La Grece est dans les fers, l'Europe est en alarmes;
Et pour comble d'horreur, l'astre au visage ardent
De ses ailes de feu va couvrir l'Occident.
Au pied de ses autels, qu'il ne saurait defendre,
Calixte, l'oeil en pleurs, le front convert de cendre,
Conjure la comete, objet de tant d'effroi:
Regarde vers les cieux, pontife, et leve-toi!
L'astre poursuit sa course, et le fer d'Huniade
Arrete le vainqueur, qui tombe sous Belgrade.
Dans les cieux cependant le globe suspendu,
Par la loi generale a jamais retenu,
Ignore les terreurs, l'existence de Rome,
Et la Terre peut-etre, et jusqu'au nom de l'homme,
De l'homme, etre credule, atome ambitieux,
Qui tremble sous un pretre et qui lit dans les cieux."

This ancient comet witnessed many revolutions in human history, at
each of its appearances, even in its later ones, in 1682, 1759, 1835;
it was also presented to the Earth under the most diverse aspects,
passing through a great variety of forms, from the appearance of a
curved sabre, as in 1456, to that of a misty head, as in its last
visit. Moreover, this is not an exception to the general rule, for
these mysterious stars have had the gift of exercising a power on the
imagination which plunged it in ecstasy or trouble.