Below the Japanese village of Aneyoshi, a 4-foot stone has stood since 1933. “Do not build your homes below this point!” it reads. “High dwellings ensure the peace and happiness of our descendants.” The village had already been devastated by a tsunami in 1896, and after a second blow the residents erected a permanent warning to those who would follow them.

It worked. A record-setting tsunami in 2011 destroyed hundreds of miles of the coast but stopped 300 feet below the Aneyoshi stone. “They knew the horrors of tsunamis,” village leader Tamishige Kimura told the New York Times, “so they erected that stone to warn us.”

Antebellum social theorist George Fitzhugh argued that slavery should be extended to whites. “It is a libel on white men to say they are unfit for slavery,” he wrote. “Catch them young, train, domesticate, and civilize them, and they would make as faithful and valuable servants as those indentured servants which our colonial ancestors bought in such large numbers from England.”

He thought that capitalism inevitably creates social inequality, and that those whom it oppresses can best be helped by subjugating them. “The whole war against slavery, has grown out of the hatred of the white to the black,” he wrote. “Nobody ever proposed to abolish white slavery, or the white slave trade. … Nobody ever proposed to abolish any other than negro slavery, and if we could buy Yankees for house-servants, and confine the negroes to field work, all this abolition strife would cease.”