The article is devoted to criticism of prophecies presented by Wojciech Bystrzonowski, an encyclopaedist and a science popularizer, in his work “Informacyja matematyczna” [“Mathematical Information”] (1743, 1749). The author discusses prophecies of sorcerers, physiognomy, palmistry, prophetic dreams and astrological predictions. He examines the cases of combining magical practices with religious beliefs, which he regards as dangerous signs of spreading superstitions. He also shows that prophecy cannot be compatible with faith and fundamental principles of rational reasoning. Furthermore, he emphasizes that in the critical evaluation of prophecy a Jesuit principle of discernment of spirits can be applied. The issues covered in his work are characteristic of the atmosphere of the intellectual change that took place at the turn of the Baroque and the Enlightenment.