before them, those
who were sent found the prison securely closed, the guards wide awake;
but having caused the doors to be opened, they found the dungeon
empty. How could an angel without opening, or any fracture of the
doors, thus extricate men from prison without either the guards or the
jailer perceiving anything of the matter? The thing is beyond any
known powers of nature; but it is no more impossible than to see our
Saviour, after his resurrection, invested with flesh and bones, as he
himself says, come forth from his sepulchre, without opening it, and
without breaking the seals,[53] enter the chamber wherein were the
apostles without opening the doors,[54] and speak to the disciples
going to Emmaus without making himself known to them; then, after
having opened their eyes, disappear and become invisible.[55] During
the forty days that he remained upon earth till his ascension, he
drank and ate with them, he spoke to them, he appeared to them; but he
showed himself only to those witnesses who were pre-ordained by the
eternal Father to bear testimony to his resurrection.

The angel who appeared to the centurion Cornelius, a pagan, but
fearing God, answered his questions, and discovered to him unknown
things, which things came to pass.

Sometimes the angels, without assuming any visible shape, give proofs
of their presence by intelligible voices, by inspirations, by sensible
effects, by dreams, or by revelations of things unknown, whether
future or past. Sometimes by striking with blindness, or infusing a
spirit of uncertainty or stupidity in the minds of those whom God
wills should feel the effects of his wrath; for instance, it is said
in the Scriptures that the Israelites heard no distinct speech, and
beheld no form on Horeb when God spoke to Moses and gave him the
Law.[56]

The angel who might have killed Balaam's ass was not at first
perceived by the prophet;[57] Daniel was the only one who beheld the
angel Gabriel, who revealed to him the mystery of the great empires
which were to succeed each other.[58]

When the Lord spoke for the first time to Samuel, and predicted to him
the evils which he would inflict on the family of the high-priest Eli,
the young prophet saw no visible form; he only heard a voice, which he
at first mistook for that of the high-priest Eli, not being yet
accustomed to distinguish the voice of God from that of a man.

The angels who guided Lot and his family from Sodom and Gomorrah