I'd like to advertise a method instead of a treatise: IMO the principle of proximity is the most important design tool. The practical application of the princi

I'd like to advertise a method instead of a treatise: IMO the principle of proximity is the most important design tool. The practical application of the principle is that space outside an element should be unambiguously larger than inner parts of the element, for the element to look like an integrated entity. This simply describes how human visual perception works. This works on all scales, from typography to graphical design to layout, even architecture. For letter spacing, kerning, line spacing, margins—apply the rule. Space between letters is obviously smaller than letters, space between words is comparable to a letter, line spacing is smaller than a line so a paragraph doesn't fall apart, margins are larger than a letter (at the least). Margins outside an element's borders are larger than padding inside. Need to pinpoint visual balance of some stuff? Consult the rule. Some things are related? Make them closer to each other than to other stuff. Bottom margin of a heading should be smaller than the top one, dammit. Margins of a list item should be larger than line spacing in it. Learn to see and apply this principle, and you'll have no problem envisioning good design in monochrome. As a side effect, you'll forever wonder why some desktop UI designers insist on separating things with noisy bars instead of empty space, seeing as the latter is hardwired in our brains. The next hella useful thing to learn is how to graphically separate layers of information, to allow people to see some related stuff and ignore everything else, instead of seeing all things at once and noticing nothing. This is where monochrome and monotonous designs break. (Also map designers love this.)