Crucifixion Diptych (van der Weyden) that they could be the left and center panels of a triptych, that they formed either the wings or shutters of an altarpiece, or that they were intended to decorate an organ case. The train of the Virgin's robe continues onto the right panel, which evidences that the panels were intended to lay side-by-side rather than separated (as the wings of an altarpiece would have been). Art historian E. P. Richardson proposed that they were the center panel of the lost Cambrai altarpiece (executed between 1455 and 1459), a single painting now split into two parts. Art historian Penny Howell
St John Altarpiece (Memling) it presents a narrative, meant to emulate a vision the donors or viewers would experience when viewing the inside panels. Unlike most altarpieces of these types, Memling's fails to present a single unifying iconographical focus and is quite generalized with themes that seem unsuited for its specific location, according to Blum. She speculates the donors may have chosen the specific iconography, which "celebrated intercessory saints on the interior". It is an unusual painting in that it seems to "have served a double function: that of personal propitiation and that of public altarpiece, which portrayed the role of the religious community