At Easter, 1791, Humboldt left Hamburg and hastened to the famous School of Mines at Freiberg, to study under the celebrated Werner. Here, as ever, he attached one ardent friend to himself, Freiesleben, a student in geology. Here every moment was occupied. He studied the works of the French chemists; Guyton de Moreau, Fourcroy, Lavoisier, and Berthollet. He was daily in the mines, from six o'clock till twelve. He crowded six lectures into each afternoon. He made a study of the vegetation of that lower world, from which the sunlight is ever excluded, and the results were used later in his comprehensive work, "Flora Subterranea Fribergensis." He wrote articles for several scientific journals. A busy life, indeed, for the young man of twenty-two! His friend Freiesleben says of Humboldt at this time:-- "The salient points of his attractive character lay in his imperturbable good-nature, his benevolence and charity, his remarkable and _unselfish amiability_, his susceptibility of friendship and appreciation of nature; simplicity, candor, and the absence of all pretension characterized his whole being; he possessed conversational powers that made him always lively and entertaining, together with a degree of wit and humor that led him sometimes to waggishness. It was these admirable qualities which in later years enabled him to soften and attach to himself the untutored savages, among whom he dwelt for months at a time, which obtained for him in the civilized world admiration and sympathy wherever he went, and which gained for him, while a mere student, the esteem and devotion of all classes at Freiberg. "He was kindly disposed towards every one, and knew how to make himself useful and entertaining in every circle of society; and it was only against every species of inhumanity and coarseness, against every kind of insolence, injustice, or cruelty, that he ever manifested either scorn or indignation." How the world loves "unselfish amiability;" a person who goes through life thinking for others, not irritable, not supersensitive, not censorious! On Humboldt's return to Berlin in 1792, he was at once made "Assessor in the Administrative Department of Mines and Smelting Works," a position for which he had previously applied. As a rule, places do not seek persons, however brilliant; they must seek places. This was a fine opening for a young man, not yet twenty-three. He went to work with unbounded energy. He investigated the general form of mountains, collected information as to former methods of working the mines, by having three chests of mining documents, belonging to the sixteenth century, brought to him for careful study, and made a report on the salt, alum, and vitriol works, and on the porcelain manufactory. The government authorities were so pleased with his thorough report that he was appointed superintendent of mines in the two Franconian duchies.