Nicholas of Causa, whose German name was Khrypffs or Krebs, was among the great church leaders of the 15th century, and on the strength of the 4th book in the present Idiota (or "man in the street"), concerning static experiments, "one of the pioneers in modern mathematical physics" whose "studies on measurements and specific gravity are of the first importance" (Thorndike, quoting Osler). The first three books are purely philosophical, and his philosophical doctrine was taken up and developed more than a hundred years later by Giordano Bruno who called him "the divine Cusanus."