Acts 12:13 Meaning

11And when Peter was come to himself, he said, Now I know of a surety, that the Lord hath sent his angel, and hath delivered me out of the hand of Herod, and from all the expectation of the people of the Jews.

12And when he had considered the thing, he came to the house of Mary the mother of John, whose surname was Mark; where many were gathered together praying.

13And as Peter knocked at the door of the gate, a damsel came to hearken, named Rhoda.

14And when she knew Peter's voice, she opened not the gate for gladness, but ran in, and told how Peter stood before the gate.

15And they said unto her, Thou art mad. But she constantly affirmed that it was even so. Then said they, It is his angel.