Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Mathias Caspar Hubert Isenkrahe (May 12, 1844 in Müntz near Jülich August 12, 1921 in Trier) was a German mathematician, physicist and catholic philosopher of nature. Caspar Isenkrahe grew up without a father, who died before Caspar's birth. Isenkrahe visited in 1856 the Progymnasium in Jülich, 1857 the Marzellengymnasium in Cologne and 1858 - 1863 the Realprogymnasium in Bonn. In 1868 he studied at the University of Bonn where he chose the subjects mathematics, physics, chemistry, mineralogy, botany, zoology, philosophy, Latin and German.