E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
something which completely changes affection. The tale is that Angelica was passionately in love with Rinaldo, who hated her, whereas Orlando, whom she hated, actually adored her shadow. Angelica and Rinaldo drink from a certain fountain, when a complete change takes place; Rinaldo is drunk with love, and Angelicas passion changes to abhorrence. Angelica ultimately married Medoro, and Orlando went mad. (Ariosto: Orlando Furioso.)