 Ida Laura Pfeiffer, one of the first female travelers who completed two trips around the world from 1846 to 1855, followed in Humboldt's footsteps.The two explorers met in Berlin in 1851 before Pfeiffer's second tour and again in 1855 when she returned to Europe.Humboldt provided Pfeiffer with an open letter of introduction in which he bade anyone who knew of his name to assist Madame Pfeiffer for her "inextinguishable energy of character which she has everywhere shown, to wheresoever's she has been called or better put, driven by her unconquerable passion to study nature and man."