Alexander von Humboldt (1769-1859) was one of the most famous personalities of his time, not only in his native Prussia but throughout the world. In addition to being a leading scientist in geography, climatology, ecology and oceanography, he attached great importance to the dissemination of knowledge to society as a whole.

He devoted much of his life to lecturing, publishing books and articles, with a determination that led him to financial ruin. Humboldt is one of the ten masters whose lives and works I have collected in the book Grandes comunicadores de la ciencia. De Galileo a Rodríguez de la source (Ed. Comares and Fundación Lilly, 2024).

It was the last years of the 18th century when Humboldt requested permission from King Charles IV to explore the Spanish colonies in America. Against all odds, the monarch authorized the trip, apparently impressed by the young man's knowledge and the arsenal of scientific instruments he carried. With them he toured Spain, taking measurements that served to demonstrate that the Iberian Peninsula is, in essence, a plateau. During the trip he aroused the suspicions of the peasants, who thought that he worshipped the moon when he made his nocturnal observations.

His journey departed from the port of A Coruña and took him, together with the French botanist Aimé Bonpland, through lands that today belong to Venezuela, Colombia, Peru, Ecuador, Mexico, Cuba and the United States. It was a real adventure, full of dangers such as the attack of a jaguar, a rough journey along the Orinoco River -which almost ended in shipwreck- or the collapse of an ice wall during the ascent to a volcano in the Andes. In this mountain range, he unsuccessfully attempted to summit the Chimborazo volcano, but set a new altitude record by reaching 5,610 meters.

The expedition served to collect data scientific information about nature: plants, animals, minerals and climates. He described about 60,000 plant species, of which about 1,500 were new to science.

Humboldt was a precursor of ecology, conceiving the universe as a system where everything is interconnected.

He was also the first to point out the effects of human action on the climate. In analyzing the transformations suffered by Lake Valencia (now Venezuela), he explained that when forests were destroyed to gain land for cultivation, springs and river courses dried up. And also that every time heavy rains fell on the summits, furrows were formed that dragged the loose soil and formed floods.

Once the trip was over, Humboldt returned to Europe and dedicated himself to making his findings known. He published 32 volumes of his Journey to the Equinoctial Regions of the New Continent (1814 and 1831). Later he published five volumes of his magnum opus, Cosmos (1845-48), conceived as a compendium of all the knowledge on natural sciences existing at the time.

Many of these books are printed in large folios containing more than 1,400 lavish illustrations by the best illustrators of the time. In their original edition, some of these volumes were so heavy that they required two people to carry them. They were very expensive publications that Humboldt himself paid for out of his own wealth staff, something that eventually bankrupted him.

His interest in democratizing science led him to use, in addition to books, other means at his disposal.

He published about 750 articles in the most important newspapers and magazines of his time, such as Allgemeine ZeitungThe Economist, The Times, The New York Times and Diario de avisos (Caracas), among many others.

Humboldt was also an extremely talented speaker. His 78 lectures, grouped under degree scroll de Cosmos (1927-28), became the social event of the moment in Berlin. His democratizing endeavor led him to open them to all interested persons, including women, who at that time were not allowed access to the university.

Humboldt himself paid out of his own pocket for the rental and heating costs of the large lecture hall conference room , where more than a thousand people gathered.

All his work has an extraordinary literary quality. In his travel diaries he makes it clear that science and poetry are not antagonistic but complementary:

"Descriptions of nature can be clearly delimited and scientifically precise without losing the life-giving breath of the imagination. The poetic character must emerge from the relationship between senses and intellect, it must emerge (...) from the inherent unity of nature itself".

Whether through written or spoken language, Humboldt was able to captivate the public, which helped him to increase his popularity and, as a consequence, his influence as a scientist. His life and his work demonstrated that Public Communication is an essential element for science.