Astolpho

(in Orlando Furioso). An English duke (son of Otho), who joined Charlemagne against the Saracens. He was carried on the back of a whale to Alcina's isle; but when Alcina tired of him, she turned him into a myrtle. He was disenchanted by Melissa. Astolpho descended into the infernal regions, and his flight to the moon (book xviii.) is one of the best parts of the whole poem. (See Inferno.)

It came upon them like a blast from Astolpho's horn

—i.e. it produced a panic. Logistilla gave Astolpho a magic horn, and whatever man or beast heard its blast was seized with panic, and became an easy captive. (Orlando Furioso, book viii.)

Like Astolpho's book, it told you everything

. The same fairy gave Astolpho a book, which would not only direct him aright in his journeys, but would tell him anything he desired to know. (Ariosto Orlando Furioso, book viii.)

Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894

Astoreth

Astolat