As early as the 17th century, Newton proposed that "swimming in molasses is slower than in water, because the viscous molasses has greater resistance than water". At the time Newton was writing his Principia Mathematica, which laid down many of the laws of physics. Newton thought that the speed of an object in a fluid depended on its viscosity, while Huygens thought it would not. Their debate remained theoretical. To finally get to the bottom of this question, Edward Cussler of the University of Minnesota and Brian Gettelfinger of the Universities of Minnesota and Wisconsin conducted a careful experiment.