Why Some People Believe That Nostradamus' Predictions Were Plagiarized
You've probably heard that Nostradamus, a 16th-century French prophet, predicted Hitler, the moon landing, and 9/11, among other things. Even in his own day, he allegedly predicted the agonizing death of King Henry II of France, a feat that earned him the patronage of the king's wife, Catherine de' Medici, according to History Hit. Considering his almanacs contained nearly 6,500 prophecies, and his separate work, "The Prophecies," contained nearly 1,000, he was bound to get it right occasionally (via Adam Smith Institute). However, University of Texas professor Rory Coker notes that modern scholars believe a lot of his predictions weren't his ideas originally.
Nostradamus could supposedly see the future by forcing himself into trance-like states via scrying and hallucinatory herbs, per History Hit. However, he never made any future predictions until adulthood. His earlier years were ordinary enough — he lived in his native Provence, got married, had kids, ran an apothecary shop, and dropped out of medical school. He may have begun dabbling in the occult because of the grief of losing his wife and children to the plague. He began making prophecies in 1547, when he was 44, per Britannica. He was publishing them by 1550 and quickly became famous (via History Channel). But how many of his prophecies were really his own?
Biblical and other sources
Nostradamus' prophecies are Christian-based. For instance, he foretold the coming of an anti-Christ and many parallel Biblical predictions. Ray Comfort, who wrote "The Secrets of Nostradamus Exposed," pointed out the similarities. Both foretold earthquakes, the dead rising from the grave, and the repossession of Israel by the Jewish people (via Baptist Press).
He may or may not have drawn directly from the Bible, however. His main source seems to have been "Mirabilis liber," a book of prophecies drawn from many different seers of the early 1500s. According to History Hit, "Mirabilis liber" included 24 Biblical quotes, which may be why Nostradamus' predictions are so similar to the Bible's.
"Mirabilis liber" was originally published in Latin and intended for scholars to read and use, so it wouldn't have been read by the general population of France. That may be why Nostradamus' prophecies were regarded as original (via University of Texas). On the other hand, the Adam Smith Institute points out that plagiarism wasn't considered "abnormal, or even unethical" in Nostradamus' time. According to their article on the topic, Nostradamus also drew from classical texts (ancient Greek and Roman) for his predictions.
Nostradamus as an astrologer
Modern scholars mostly agree that Nostradamus couldn't really see the future. They think he believed history would repeat itself, so he used past events to predict future ones (via History Channel). This explains why, according to Professor Coker, his prophecies describe "universal" events like famines, plagues, wars, conquests, and revolutions — things that had happened many times before and thus were likely to happen again.
For his research into the past — and thus his predictions of the future — he may have used bibliomancy. This involved choosing older sources and excerpts randomly. Then, based on what he found in these sources, he used astrological calculations to extrapolate the possible recurrence of the past events he was reading about. The History Channel says many of his astrological references came from "Livre de l'estat et mutations des temps" (The book of the state and mutations of time) by Richard Roussat.
Ironically, his contemporary astrologers weren't too impressed with his work in their field. They considered his methodology haphazard and inaccurate. One even published a pamphlet denouncing him. However, outside the astrology community, Nostradamus was popular in his own time and remains so today, whether or not his ideas were really his.