In the œuvre of Michel Sittow, it is the portrait of a beautiful young lady in Vienna, Kunsthistorisches Museum, that becomes a candidate for intense search. The proposed identification with Princess Catherine of Aragon somehow acquired an almost general acceptance but an analysis of the only three small details used for bracing the hypothesis, reveals their fragility. One is the letter "K" cast and carved alternatively with a rosette on a necklace of the lady. It is held to stand for Catherine and the other for the rose of Tudor. The third monogram adorning the center of her white undershirt in the broad neckline is even more unclear and might even be a ligature of two letters and not a "C". Our search takes us to the portions painted on the outer surfaces of the wings of the Passion triptych commissioned by the Fraternity of St. Anthony in Reval which is not accorded a more coverage in the discussion of Sittow's œuvre that is deserves.
At the end, contemplation of the phenomenon of ideal feminine beauty created in three related images (Vienna, Berlin, Detroit) is given still a larger dosage of the hypothetical in an attempt to involve in the creation of this beauty Michel's father Clawes van der Sittow and a remarkable, strongly Netherlandish-inspired painting in Iserlohn, Westphalia.