A surgeon is in the process of removing with a knife a stone (believed to be the stone of madness), which is visible inside an incision in the patient's open skull. The madness of the patient was believed to disappear with the removal of the stone. It is implied that the surgeon is actually a quack who has himself placed the stone in the incision by a sleight of hand before pretending to remove it. As an advertisement for his skills there is behind him a line on which hang stones, which he has supposedly removed from earlier patients. Next to the surgeon stands a man who is gesturing in desperation, as he is clearly the next patient to go under the scalpel. On the left a female assistant is preparing ointment in a bowl. The composition is a denunciation of the greed of the surgeon who abuses his patients' gullibility. His style of portrait painting played an important role in the popularity of portraiture in northern Europe from circa 1540 onwards. While Michelangelo and Raphael were the principal influences on his religious compositions, his later portraiture owed more to Agnolo Bronzino. At the same time, his portraits include elements from Flemish painting of his time. An example of his portraits is the "" dated between 1530 and the early 1540s (sold at Sotheby's on 9 July 2014 in London, lot 41, fetching £1,762,500). It is clearly inspired by Bronzino's portraits from the 1530s, which van Hemessen must have known through prints. The "Portrait of a Gentleman" shows an arrangement of the hands typical for Bronzino but started by Titian: the right hand is grasping an item representative of the sitter’s interests or identity, while the other hand rests lower down the plane. This arrangement would become standard practice in High Renaissance and Mannerist portraiture. An important element in van Hemessen’s work differs from his Itialian model: the landscape. Beyond the sitter is visible a ‘world landscape’ in the more developed form as it was practised in the Low Countries in the 1530s and reminiscent of the landscapes of Matthys Cock.