Virgin and Child, wood with polychromy, 154.9 x 53.3 x 45.1 cm, French, 1210-25.
Medievalists (my former professor Jacqueline Jung is at the forefront of this movement) have been critiquing photography and display practices for their flattening effect on some sculpture. Here, for instance, the picture is taken from an unnaturally high angle. From lower down, it is possible to meet the Virgin's gaze, and the statue takes on a much more serious dimension:
(My apologies for the shoddy picture)
One should always, when encountering sculpture even more than two-dimensional work, move around, forward and backwards, and up and down. Although this is useful to get a grasp on the piece as a whole, it also helps to uncover the priviledged viewpoint(s): in this case, the moment(s) when the statues become interlocutors, engaged in a dialogue with us. This happened when my eyes were level with Mary's feet (incidentally, other museum visitors seem to frown on kneeling in galleries), which tells you something about at least some subset of original viewing conditions.
About another factor, however, i can only speculate: the effects of variable light. Lit by windows and candles, all medieval sculpture was much more mobile in situ than it is in museum galleries. In this case, for instance, the deep folds of the cloak at Mary's throat presumably caught more motion than the rest of the sculpture, leading to the appearance of movement in the head. Furthermore, i suspect that the very spare carving of facial features, much less detailed than the draperies, had a great deal to do with variable light as well: given that it is cast shadows which enable us to read the faces, having a relatively unspecified expression, but with a relatively deeply carved mouth in particular, might allow for manipulation in a ritual context.She seems benevolent and serene in this even lighting - might she not be somewhat foreboding in others? Without experiments, it is hard to say.