“Visual activation of negative areas of white space in these exhibits illustrates the endlessly contextual and interactive nature of visual elements. This idea is captured in a fundamental principle of information design: 1 + 1 =3 or more. In the simplest case, when we draw two black lines, a third visual activity results, a bright white path between the lines … Most of the time, that surplus visual activity is non-information, noise, and clutter ” Envisioning Information by Edward R. Tufte p.61
A Single line is just a line, but if you add another parallel line to it, a third object is created, and that object is the WHITE SPACE/ NEGATIVE SPACE
So 1+1=3 and White/Negative Sxpace was the first thing I ever learned about principles of Design.