The Marxists had it right all along, they just got tripped up by their materialism. Early modern capitalism opened vast new worlds, particularly in the arts and sciences, only the traffic went both ways. Creative agents invented new markets and pushed commerce in directions that favored enterprises immensely cosmopolitan and innovative, often solely for the sake of beauty and display. Commerce offered a context but the nobility, and not an imagined bourgeoisie, had the edge when it came to exploiting the market for objets. Paintings could be traded for property, land, and houses. Princes could sponsor natural philosophers, and the fluidity in values meant that good investors, like good practitioners of the arts and sciences, took an interest in all aspects of learning. The interrelatedness of the representational arts and natural philosophy stands as one of the central themes in this tightly integrated collection of essays. We now have a vast historiography telling us that we should no longer teach early modern science without reference to the art of the time, and vice-versa. The point is beautifully illustrated by an exhibition recently held at the J. Paul Getty Museum in Los Angeles (spring 2002) on the art of Pieter Saenredam. Working in Utrecht in the 1630s, he used geometry to regularize and make precise the angles and corners found in the exquisite paintings he made of the city's churches. He knew as much about geometry as he did about chiaroscuro. At precisely the same moment, an hour or two away by barge, Descartes in Leiden put the final touches on his Discourse on Method (1637). In effect he explained to the world why precision and clarity of thought made possible the kind of beauty that Saenredam's paintings would come to embody.