Heavenly Relics as Means to Raise Money for Earthly Projects

Like many churches, the Castle Church of Wittenberg where Luther would nail his 95 theses had relics. More than 19,000 of them. The collection of relics included a twig from Moses' burning bush, four hairs of the Virgin Mary, five particles of her milk, a piece of Jesus's swaddling clothes, two pieces of hay from the manger, five pieces of the table from the Last Supper, and eight thorns from Jesus's crown. These were put on display once or twice a year.

Each relic had an associated indulgence that reduced the time a sinner had to spend in purgatory by days or years. Added together, the relics in the church collection could bring about a reduction of precisely 1,902,202 years and 270 days in purgatory.

That may have been the origin of the "must see" exhibition.

Oh, and they then used the money collected by people come to see the exhibit to fund bridges, dikes, schools, hospitals, and cathedrals. People were willing to pay for what they imagined and the authorities used that to pay for what was real. That's an interesting governance model and may have actually been more sustainable than the one we have now.