When you look at one of Joseph Mallord William Turner’s paintings, you might notice his work with color.

Yes—while it is a landscape painting, and landscapes were seen as a relatively low form of art at the time, that Turner took on any way for better commercial prospects—it’s also much more than what even a photograph might show you. “My business is to paint what I see, not what I know is there,” he’s quoted as saying.

Turner’s practice, which involved him sketching to document what he saw and, as a byproduct, constantly studying color and shape, was simple: travel and paint. There were no Marriott points back then—travel was difficult and painful.

In order to document what he saw, he would need to quickly sketch or paint it out. In other words, he sketched to think. Three centuries prior to Turner, Leonardo da Vinci called this, “componimento inculto,” which biographer Walter Isaacson describes as “an uncultivated composition that helps work out ideas through an intuitive process.” Turner did this work in notebooks of all sizes, some just a little larger than a thumb. 
This practice led him to create and complete a vast quantity of work: more than 550 oil paintings, 2,000 watercolors, and 30,000 works on paper. More importantly, it enabled him to create the art that he wanted to make, within the constraints of his time.