This biography of Alexander von Humboldt, the German scientist, explorer and statesman whose work did much to usher in the modern era of discovery, has been written with an awareness and a freshness of style that does much to place him in vivid perspective for a reader audience whose interest in natural science continues to rise. Perhaps the first of Humboldt's contributions that comes to mind is the sea current that bears his name. But its discovery was a single facet in a life that marked him as a man of encyclopedic interests. Born into an aristocratic family, Humboldt suffered from the loveless, dry propriety of his upbringing and to a certain degree had to kick over the traces of convention to follow his bent. Study and university training prepared him for work in the department of mines and brought him at last to the point where he could begin to travel and carry out his own observations. Journeys in South America with Bonpland included expeditions in the Amazon, the Andres and Mexico where his notations on weather and geological conditions combined with archeological discovery and speculation to contribute to the opening up of new eras and areas. They brought him fame when he returned to Paris and thenceforth decreed, that he was to live as a man with public influence. For Humboldt returned to Berlin to play an often ironic role as advisor to the King. A full and fascinating study here is as astute in its rendition of the relationships in Humboldt's studies as it is in its observations of men.