The Island of the Day Before is an adventure story set in 1643. The main character, the young Italian nobleman Roberto, is shipwrecked aboard the Amarilli (in the English version translated as Amaryllis). He winds up on a Dutch vessel then known as a 'fluyt' — in Dutch, the same word for 'recorder'. The ship is called the Daphne. And in his imagination there is another ship called the Tweede Daphne, "that is to say, Daphne the Second, a sign […] that somewhere there must be a Daphne the First, which showed how those Protestants lacked not only faith but also imagination." (transl. W. Weaver, p. 403)

It was early morning, and Roberto again was dreaming. He dreamed of Holland. It was while the Cardinal's men were conducting him to Amsterdam to put him on the Amaryllis. During the journey they stopped at a city, and he entered the cathedral. He was impressed by the cleanliness of the naves, so different from those of Italian and French churches. Bare of decorations, only a few standards hanging from the naked columns, the glass windows plain and without images: the sun created there a milky atmosphere dotted only by the few black forms of the worshippers below. In that peace a single sound was heard, a sad melody that seemed to wander through the ivory air, born from the capitals or the keystones. Then he noticed in one chapel, in the ambulatory of the choir, a man in black, alone in one corner playing a little recorder, his eyes staring into the void.

When the musician finished, Roberto went over to him, wondering if he should give him something; not looking into Roberto's face, the man thanked him for his praise, and Roberto realized he was blind. He was the master of the bells (der Musicyn en Directeur van de Klokwerken, le carillonneur, der Glockenspieler, he tried to explain), but it was also part of his job to delight with the sound of his flute the faithful who lingered at evening in the yard and the cemetery beside the church. He knew many melodies, and on each he developed two, three, sometimes even five variations of increasing complexity, nor was it necessary for him to read notes: born blind, he could move in that handsome luminous space (yes, he said luminous) of his church, seeing, as he said, the sun with his skin. He explained how his instrument was so much a living thing, that it reacted to the seasons, and to the temperature of morning and sunset, but in the church there was always a sort of diffuse warmth that guaranteed the wood a steady perfection-and Roberto reflected on the notion of diffuse warmth a man of the north might have, for he himself was growing cold in this clarity.

The musician played for him the first melody twice more, and said it was entitled "Doen Daphne d'over schoone Maeght." He refused any offering,touched Roberto's face and said, or at least Roberto understood him to say, that "Daphne" was something sweet, which would accompany Roberto all of his life.

Now, on the Daphne, Roberto opened his eyes and, without doubt, heard coming from below, through the fissures in the wood, the notes of "Daphne," as if it were being played by a more metallic instrument which, not hazarding variations, repeated at regular intervals the first phrase of the tune, like a stubborn ritornello.

He told himself at once that it was a most ingenious emblem: to be on a fluyt named Daphne and to hear music for flute entitled "Daphne." It was pointless to persist in the illusion that this was a dream. It was a new message from the Intruder.

Eco evokes splendid, poetic images, although they do not always tally with actual historical circumstances.

The melody Roberto hears is produced by a water organ with twenty pipes, "which Father Caspar had taught him how to set in motion: he heard always and only 'Daphne,' because he had not learned how to change the cylinder; but he was not sorry to listen hour after hour to the same tune." (p. 342)