Jewish History: Biblical History: The Egyptian Magicians:
How were the Egyptian magicians able to duplicate the first two plagues?
The classical commentaries had no problem with the Egyptian magicians
being able to duplicate the first two plagues, because they accepted the
existence of demons and magic (see Rashi on Ex. 7:22). But they also
point out (ibn Ezra, ibid.) that the magicians did only small-scale things
("changing" a small amount of water to "blood"; producing one or two frogs),
and these things could have easily been done by sleight of hand.
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