They are simultaneously sacred texts and works of art, three illuminated Byzantine-era manuscripts that are more than 1,000 years old and that for decades have been part of a heralded collection at Princeton University.

The college received the items as a gift in 1942 from a trustee and alumnus who had bought them from a German auction house nearly 20 years earlier.

But in a lawsuit filed Thursday, the spiritual leader of the Eastern Orthodox Church said the manuscripts were stolen and demanded their return, asserting that they had been taken during World War I from a monastery in Kormista, a village in northern Greece.