That Alexander von Humboldt was not dead by the age of thirty-five was a minor miracle. In 1794 he nearly suffocated while testing his miner’s lamp in a subterranean tunnel. The next year he subjected his body to such an extreme series of galvanic experiments that his doctor felt compelled to intervene. In 1800, among the ceiba trees beside the Apure River in Venezuela, he disturbed a resting jaguar (‘never had a tiger appeared to me so enormous’). On that occasion, Humboldt tiptoed to safety, but weeks later he almost paralysed himself while pulling on a sock contaminated with curare, the lethal arrow poison.
Humboldt’s narrowest escape of all, perhaps, came in 1802, during one of his series of high-altitude ascents in the mountains of Ecuador. Nearing a summit, he glanced down to see a bluish light glowing through the snow. He smelled sulphur. ‘He realised with a shudder,’ writes Maren Meinhardt in this evocative and perceptive biography, that he and his companion ‘were on top of the crater itself’. The only thing separating them from the volcano was a ‘thin bridge of compacted snow’.
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