Hans Memling's 1487 diptych Virgin and Child and Maarten van Nieuwenhove is one of the most celebrated Early
Netherlandish paintings, but little is known about the practical use of such objects in late medieval devotional
practice. A particular point of debate, spurred by the reflection in the painted convex mirror behind the Virgin,
concerns the question if the two hinged panels were to be used while set at an angle, and, if so, at what angle.
It was recently discovered that the mirror was not part of the painting's initial design, but instead added later
by Memling. We created a simple computer graphics model of the tableau in the diptych to test whether the
image reflected in the mirror conformed to the image of the model reflected in the mirror. We find two significant
deviations of the depicted mirror from that predicted from our computer model, and this in turn strongly suggests
that Memling did not paint the mirror in this diptych while viewing the scene with a model in place, but that
the mirror was more likely painted without a model present. In short, our findings support the notion that the
mirror was an afterthought. This observation might have implications for the understanding of how the diptych
was used in devotional practice, since it affects the ideal viewing angle of the wings for the beholder.