The absent-minded professor There are three variants of procrastination, depending on what you do instead of working on something: you could work on (a) nothing, (b) something less important, or (c) something more important. That last type, I'd argue, is good procrastination. That's the "absent-minded professor," who forgets to shave, or eat, or even perhaps look where he's going while he's thinking about some interesting question. His mind is absent from the everyday world because it's hard at work in another. Paul Graham, Good and bad procrastination procrastinationproductivity
Paths, edges, districts, nodes, landmarks The contents of the city's images which are referable to physical forms can conveniently be classified into five types of elements: paths, edges, districts, nodes, and landmarks. Paths are the channels along which the observer customarily, occasionally, or potentially moved. Edges are the linear elements not used or considered as paths by the observer. They are the boundaries. Districts are the medium-to-large sections of the city, conceived of as having two-dimensional extent. Nodes are points, the strategic spots in a city into which an observer can enter, and which are the intensive foci to and from which they are traveling. Landmarks are another type of point-reference, but in this case the observer does not enter within them, they are external. They are usually a rather simply defined physical object: building, sign, store, or mountain. Kevin Lynch, The Image of the City City districtsAs a kind of gateway cities