"I got the recollection and the blood of the Lamb!"
Adoration of the Lamb, from the Ghent Altarpiece
Public DomainAdoration of the Lamb, from the Ghent Altarpiece - Credit: Jan van Eyck

The Lamb appears in the Bible and medieval mystical texts, such as the Pearl poem, as an avatar of Christ. The blood figures divine salvation.

 

These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb. (Revelation 7.14)  

Paschal Lamb
Public DomainPaschal Lamb - Credit: Josefa de Óbidos