There’s a silver mother and child icon in every house on the Greek island of Paros, so what’s the story? Friend and local Paraskevi tells me: “You’ll find the original in Ekatontapiliani, the Church of 100 Doors.”

Two minutes from the sea, hidden from the bustle of Parikia’s port, the fourth-century church is all arches, dome and windows (although there aren’t 100 doors). I light a candle and walk to the glittering Madonna, a Byzantine icon covered with silver in 1788. I queue, kiss the child, then sit.

There are pots of basil outside, lovingly tended in memory of ninth-century nun Osia Theokisti, who lived alone on the island for 35 years after escaping from pirates, surviving on wild basil and holy water. On either side of the shrine, deep in the foundations and visible through a glass floor, are marble pillars from a Grecian temple to Aphrodite, which stood here before. Every August, villagers carry icons of Mary down to the sea, with fireworks and partying. Surely such festivities date back to the rites of ocean-born Aphrodite, when clay effigies were thrown into the ocean?

• Xanthe Gresham-Knight is touring the UK in Adverse Camber’s The Shahnameh: The Epic Book of Kings, from 19 October, adversecamber.org