Half as many people will not support half as many enterprises In a given geographical territory, half as many people will not support half as many such enterprises spaced at twice the distance. When distance inconvenience sets in, the small, the various and the personal wither away. Jane Jacobs, The Death and Life of Great American Cities densitydistancegeographybusinesseconomics
highdensityandovercrowding They hated both equally, in any case, and coupled them like ham and eggs, so that to this day housers and planners pop out the phrase as if it were one word, “highdensityandovercrowding.” Jane Jacobs, The Death and Life of Great American Cities densityurbanism
Making coal miners into programmers Many humans at present are not equipped to compete with machines—they are unable to do much more than routine jobs. There is a widespread belief (hope?) that humans can compete, once they are given proper training. However, I have long publicly doubted you could take many coal miners and make them into useful programmers. Richard Hamming, The Art of Doing Science and Engineering: Learning to Learn Manual labor