An Ambrose-stone (Spell)

From Egyptian Secrets of Albertus Magnus, Joseph H. Peterson edition:

An Ambrose-stone.

Steal the eggs of a raven, boil them hard, lay them again into the nest and the raven will fly across the sea and bring a stone from abroad and lay it over the eggs and they will beĀ­come at once soft again. If such a stone is wrapped up into a bay leaf and is given to a prisoner, that prisoner will be liberated at once. Whoever touches a door with such a stone, to him that door will be opened, and he who puts that stone into his mouth will understand the song of every bird.

Timeline of related events

1900

1950

In this decade: Publication of The Book of Forbidden Magic (lists this spell)