I had a most interesting conversation with a woman whose family is descended from Converso Jews in Spain.

These are Jews who pretended to convert to Catholicism but continued to practice Judaism in secret. They didn’t act very good and neither did the local Jews. The local Jews had had a large population around Toledo. Sadly there were also many pogroms in this city over time. The local Jews in this area routinely damaged and destroyed Christian monuments and symbols. They sometimes murdered Christians who wandered into the Jewish district during the Sabbath. These are the things you never hear about when you hear the sanitized version of Jewish history in Europe.
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This woman told me she had been studying her family’s history for over 20 years. She had even made trips to the Library of Congress. She told me that her family has a long passed-down oral tradition of being Converso Jews in Spain. Soon before the Inquisition (probably in the area around Toledo referenced above), according to her family history, her family and probably other Conversos had been poisoning the wells of Christians. This apparently killed the Christians. After the property was left vacant by the dead Christians, her family and presumably other Conversos would swoop in and steal it.
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This makes sense to me. A lot of these “antisemitic canards” are based on the idea that millions of people all over the world all across space and time made up complete lies out of whole cloth about the Jewish people. They said things happened that never happened. They said things never happened that did happen. This was before jets, planes, cars, trains, phones, radios, TV’s, or Internet.
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But Jews got accused of poisoning wells in multiple places. Why would they be accused of this if it were not true? One thing you will find is that millions of people don’t typically make horrible lies about other groups that stretch across thousands of miles and centuries. Why would anyone do that?