They are part of a new iconographical tradition led by Claus Sluter that continued until the end of the fifteenth century.
In this tradition, free-standing sculptures depict mourners who stand next to a bier or platform that holds a body in state.
[1] The Dutch historian Johan Huizinga described the tomb as the "most profound expression of mourning known in art, a funeral march in stone.
There are priests, monks, members of the ducal household, choirboys -- all demonstrating their grief and pain most eloquently, some with eyes turned toward the heavens, others wiping their tears on their sleeves ...
[4] When Mackay died, his estate sold the sculptures to the Cleveland Museum of Art, where they remain today.