You live only once The logician would argue, You only live once should be rewritten as You live only once, with only next to the thing it qualifies, once. The logician would be unbearably pedantic, but there is a grain of good taste in the pedantry. Writing is often clearer and more elegant when a writer pushes an only or a not next to the thing that it quantifies. In 1962 John F. Kennedy declared, “We choose to go to the moon not because it is easy but because it is hard.” That sounds a lot classier than “We don’t choose to go to the moon because it is easy but because it is hard." Steven Pinker, The Sense of Style grammar
The requirements of economy Economy is the mother of most inventions, not necessity, unless in the sense of poverty and hardship. A requirement for convenience is simply a diluted requirement for ease and economy. It seems to be invariably true that those characteristics which lead people to call a design functional are derived from the requirements of economy and not of use. David Pye, The Nature and Aesthetics of Design Form follows functionEconomy of material and labor function