Humboldt's researches into the vegetation of the mines of Freiberg led to the publication in Latin (1793) of his Florae Fribergensis, accedunt Aphorismi ex Doctrina, Physiologiae Chemicae Plantarum, which was a compendium of his botanical researches. That publication brought him to the attention of Johann Wolfgang von Goethe, who had met Humboldt at the family home when Alexander was a boy, but Goethe was now interested in meeting the young scientist to discuss metamorphism of plants. An introduction was arranged by Humboldt's brother, who lived in the university town of Jena, not far from Goethe. Goethe had developed his own extensive theories on comparative anatomy. Working before Darwin, he believed that animals had an internal force, an urform, that gave them a basic shape and then they were further adapted to their environment by an external force. Humboldt urged him to publish his theories. Together, the two discussed and expanded these ideas. Goethe and Humboldt soon became close friends.