A peculiarity of the picture is the exceedingly simple setting in which the figures are placed; whereas Holbein’s usual practice at this period of his life was to make an almost lavish use of architectural ornamentation in his backgrounds. In the “Solothurn Madonna” it consists of a perfectly plain round archway of stone, quite free from sculptured decoration, across which two thick iron bars are placed, fixed into the stonework as though to strengthen it, with upright cross bars running to the crown of the arch. It has been suggested that the vaulting of the church for which the picture was intended was supported and strengthened in the same way, and that Holbein introduced it into his altar-piece in order that it might be in perfect harmony with its surroundings; but the motive appears in more than one of the backgrounds to Ferrari’s pictures, such as the “Flagellation,” one of the great series of frescoes in the church of S. M. delle Grazie, at Varallo,[233] finished in 1513. Through this open archway a pale-blue sky is seen, against which the Virgin’s crown stands out. The light increases in brightness as it nears the Madonna’s head, thus forming a natural halo. This simplicity of treatment is also to be observed in other details. The Virgin is not seated upon an elaborate throne, but on some low seat or stool which cannot be seen. The carpet at her feet, covering the stone step, is green, with a geometrical diamond pattern in white and red, and two shields inset containing the arms of the donor and his wife,[234] which are partly hidden and protected by the Virgin’s cloak. Below St. Ursus the monogram “H. H.” and the date “1522” are painted as though cut in the stone step. The Virgin and the Infant Christ in this picture appear to be idealised portraits of Holbein’s wife and first-born child. All available evidence indicates either 1520 or 1521 as the date of his marriage, shortly before or after he became a citizen of Basel, so that his own child may well have served him as his model. Hans Bock the elder, the artist who was employed by the Basel Council to renovate Holbein’s wall-paintings in the Town Hall, made a free copy of the figure of the Child in this picture when he was in Solothurn in 1604 or the following year, and depicted him with a serpent as the conqueror of sin.[235] This copy, now in the Basel Gallery (No. 91), belonged to Amerbach, and was entered in the catalogue as “A naked child sitting on a serpent, a copy of a painting by Holbein, exactly copied in the greater part by H. Bock on wood in oil colours.”[236] Woltmann describes a drawing of the same child’s head, almost in profile, with the mother’s hand supporting it under the left shoulder, as in the picture, in the Weigel Collection, Leipzig, a silver-point drawing, signed and dated, “Hans Holbein, 1522.”[237] It has the same large, rather round head, short neck, and high forehead, as in the painting, and it was probably a preliminary sketch for it.[238]