Similar (of course, far from identical) irritations in similar conditions call out similar reflexes; the more powerful the irritation, the sooner it overcomes personal peculiarities. To a tickle, people react differently, but to a red-hot iron, alike. As a steam-hammer converts a sphere and a cube alike into sheet metal, so under the blow of too great and inexorable events resistances are smashed and the boundaries of "individuality" lost.