Since the advent of infrared photography and in particular infrared reflectography (Note I), study of the underdrawing has increasingly become a fundamental part of art historical and stylistic analysis. There are, however, more unforeseen pitfalls here than in the study of the finished painting and analysis of the underdrawing actually involves an even greater understanding of and feeling for the medium and the motives, methods and aims of the artist. Hans Memling is exceptional in that he proves often to have drawn freehand directly on the ground, instead of transferring on to it the main lines of a composition worked out elsewhere (Note 2). This explains the confused and much corrected images revealed by infrared reflectography, but this is not a case of his being an 'expressionistic' draughtsman, as opposed to a serene painter. The nature of the drawing is largely due to his method of working out his composition: Memling reveals on the panel what most artists did somewhere else. His predilection for drawing directly on the panel is clearly apparent in the Portrait of Maarten van Nicuwcnhove of I487 (Fig. I), the right side of a diptych with the Madonna, which is one of the few, if not the only painting of this period in the Netherlands in which the geometrical working out of the perspective construction can be seen in the underdrawing. The construction lines, which can be seen quite clearly with the naked eye in the lighter areas, were thought by Tulpinck (Note 3) to be connected with an ingenious theory of proportion applied by Memling, while Taupert (Note 4) interpreted them on the basis of an infrared photograph (Fig. 2) as a detailed working out of the prespective, which Memling largely ignored, apart from the main lines, when he actually started painting. In a recent analysis by Hollanders-Favart (Note 5), all the lines revealed by infrared light have been amplified into a remarkable scheme (Fig.3), from which the conclusion is correctly drawn that three types of construction lines were used: parallel vertical lines, orthogonals converging on a single vanishing point on the left side of the diptych and diagonals linking some of the intersections of the first two types of line. It is then further argued that the vertical and diagonal lines are compositional elements which help to determine the placing of the figure in the space. In fact, however, the whole construction is simply and solely concerned with the precise determination of the positions of the sides of the windows and to this end the diagonals were not drawn after the vertical lines, but before them, to denote their positiona. Moreover, the orthogonals and the vertical lines do not run over the head, which must thus have been drawn in before them. The method was therefore the opposite way round to that suggested by Hollanders-Favart. The volume of the head was first placed in the centre of the panel, on the intersection of the horizon and the central vertical axis, and the rest of the figure may have been summarily indicated at that point. Then Memling drew the perspective scheme to define the oblique wall behind the figure, which he divided into four sections of equal width with a window and an area of wall alternately (Fig.4). Thus this constructional scheme had nothing to do with the placing or proportions of the figure, which is not done in accordance with that perspective, albeit the final positioning of the thumbs may well have been conditioned by the central vertical line, as Hollanders-Favarl suggests.