The Latin formula ex voto suscepto, from the vow undertaken, names a transaction older than Latin. A petitioner in trouble promises a deity something if the prayer is granted; the ex-voto is the payment, delivered to the sanctuary and left in public view. Ancient Mediterranean religion ran on the practice at scale. Greek healing sanctuaries of Asklepios received carved and molded body parts, eyes, ears, legs and wombs, marking cures; Italic sanctuaries have yielded anatomical terracottas by the thousand; and inscribed stone votives survive across the Roman world with the abbreviation VSLM, votum solvit libens merito, meaning the dedicator paid the vow willingly and deservedly.
Christianity inherited the grammar and changed the addressee. Shrines of the saints and of the Virgin accumulated wax limbs, silver hearts, crutches, model ships from sailors saved at sea, chains from freed captives. Catholic teaching distinguished such offerings from magic by their logic of thanksgiving: the object does not compel a favor, it commemorates a grace received.
The habit's persistence is its most striking feature. Walls of marble plaques reading only grazia ricevuta or merci line the pilgrimage churches of Europe, and the halls at Lourdes and Guadalupe hold thousands of testimonies. Whatever the theology above them, the offerings speak a constant language of debt acknowledged and paid.