transubstantiation
Concept
The doctrine that bread and wine are changed into the body and blood of Christ during communion, relevant around the time Wolfram von Eschenbach wrote.
Mentioned in 2 videos
Videos Mentioning transubstantiation

The Best Kept Secret In History?: A Conversation with Brian Muraresku (Episode #346)
Sam Harris
The Catholic doctrine that the bread and wine of the Eucharist literally become the body and blood of Christ, a concept many modern Catholics reportedly do not believe in.

The Quest for the Holy Grail (The Self)
Eternalised
The doctrine that bread and wine are changed into the body and blood of Christ during communion, relevant around the time Wolfram von Eschenbach wrote.