Of Bol’s capacity in portrait-painting a good example is _Portrait of a Mathematician_, in the Louvre. He is shown resting one arm on a balustrade, the body, in black with a white collar, being in profile, while the gray-haired head, covered with a black cap, is facing round to the spectator, as he points with a ruler to a geometrical figure on a blackboard. It is a piece of honest characterization, blending vivacity and dignity. In quite a different vein is his portrait of a girl in profile in the Liechtenstein Gallery. She has soft pale blond hair, and the figure is enveloped in that yellow tonality which marks Bol’s transition from the Rembrandtesque manner to his later one. The girl with her protruding forehead bears a striking resemblance to a girl, painted by Rembrandt, in Room VI of the same gallery, and a comparison of the two pictures offers an interesting commentary upon the essential difference between the master and one of his most successful pupils. Among five portraits by Bol in the Munich Pinakothek No. 338 may be specified as particularly handsome. It is that of a man with dark-brown hair and a mustache and imperial of lighter hue, possibly Govert Flinck. He wears a black cap and cloak and leans his arm upon a table. The following number in the catalogue is allotted to a portrait of this man’s wife. She is shown as far as the waist, where her hands are folded, the body full front, the head a little to the left. The face is beautifully modeled in clear flesh-tones, surrounded by golden-brown hair in ringlets. Beneath her white stomacher is a dull-red gown with olive sleeves. Thus the color-scheme is Rembrandtesque, with an envelop of warm amber atmosphere, while the serious sympathy with which the characterization has been rendered would not be unworthy of Bol’s great master.