Doctor of Philosophy | philosophy | Philosophy | Nature | International Union for Conservation of Nature | Nature (journal) | nature reserve | World Wide Fund for Nature | Naughty by Nature | nature | Jewish philosophy | The Nature Conservancy | Nature reserve | National Museum of Nature and Science | Indian philosophy | Chinese philosophy | Mother Nature | Islamic philosophy | University of Belgrade Faculty of Philosophy | nature documentary | Juma Nature | Human Nature | Yellingbo Nature Conservation Reserve | Two Against Nature | Tsingy de Namoroka Strict Nature Reserve | Philosophy of mathematics | philosophy of mathematics | Objectivity (philosophy) | Human Nature (Doctor Who episode) | Flói Nature Reserve |
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.