Rembrandt "Danaë", 1636), seeking to emulate the baroque style of Rubens. With the occasional help of assistants in Uylenburgh's workshop, he painted numerous portrait commissions both small ("Jacob de Gheyn III") and large ("Portrait of the Shipbuilder Jan Rijcksen and his Wife", 1633, "Anatomy Lesson of Dr. Nicolaes Tulp", 1632). By the late 1630s Rembrandt had produced a few paintings and many etchings of landscapes. Often these landscapes highlighted natural drama, featuring uprooted trees and ominous skies ("Cottages before a Stormy Sky", c. 1641; "The Three Trees", 1643). From 1640 his work became less exuberant and more sober in tone, possibly
Nicolaes Tulp but also because of the fantastic stories that he relates. An example; Jan de Doot, a blacksmith in Amsterdam, was in such pain from a bladder stone, that he sharpened a knife and removed it himself, because he refused to be the victim of the 'stone cutters'. These were the barber-surgeons who performed such procedures but had a high death rate. To everyone's surprise, Jan de Doot survived this operation which was said to produce a stone the size of an egg. A painting illustrating this story is in the collection of the Anatomy Museum of Leiden. Tulp minutely described