| Link | Quote | Stars | Tags | Author |
| 035a9fd | The first problem of living is to minimize friction with the crowds that surround you on all sides. | population-density urban-life | Isaac Asimov | |
| 0f9cdda | The meteorites of 1908 and 1947 had struck uninhabited wilderness; but by the end of the twenty-first century there was no region left on Earth that could be safely used for celestial target practice. | meteors population-density space | Arthur C. Clarke |