The Invention of Nature

Armed with his hat as a ‘botany box’ in which he kept plant specimens fresh during the long walks, a heavy music book as his plant press, a spyglass and his walking stick as a measuring tape, Thoreau now explored nature in all its detail. During his walks, he wrote notes on small scraps of paper which he then expanded in the evenings for his longer journal entries. His botanical observations became so meticulous that scientists still use them to examine the impact of the changing climate – by comparing the first flowering dates of wildflowers or the ‘leafing out’ dates of trees from Thoreau’s journals with those of today.

‘I omit the unusual – the hurricane and earthquakes – and describe the common,’ Thoreau wrote in his journal, ‘this is the true theme of poetry.’ As he meandered, measured and surveyed, Thoreau was moving away from Emerson’s grand and spiritual ideas of nature and instead observed the detailed variety that unfolded on his walks. This was also the moment when Thoreau first immersed himself in Humboldt’s writings – at the same time as he was turning against the influence of Emerson. ‘I feel ripe for something,’ Thoreau wrote in his journal. ‘It is seed time with me – I have lain fallow long enough.’

Thoreau read Humboldt’s most popular books: Cosmos

, Views of Nature and

Personal Narrative. Books on nature, Thoreau said, were ‘a sort of elixir’. As he read, he was always noting and scribbling. ‘His reading was done with a pen in his hand,’ one friend remarked. During these years, Humboldt’s name appeared regularly in Thoreau’s journals and notebooks, as well as in his published work. Thoreau noted ‘Humboldt says’ or ‘Humboldt has written’. One day, for example, when the sky had glowed in a particularly bright shade of blue, he felt the need to measure it precisely. ‘Where is my cyanometer?’ Thoreau called out. ‘Humboldt used it in his travels’ – referring to the instrument with which Humboldt had measured the blueness of the sky above Chimborazo. When Thoreau read in Personal Narrative

that the roar of the rapids of the Orinoco was louder at night than by day, he noted the same phenomenon in his journal – only that the thunderous Orinoco was a gurgling brook in Concord. To Thoreau’s mind the hills that he had hiked in Peterborough in neighbouring New Hampshire were comparable to the Andes, while the Atlantic became a ‘large Walden Pond’. ‘Standing on the Concord cliffs,’ Thoreau wrote, he was ‘with Humboldt’.

What Humboldt had observed across the globe, Thoreau did at home. Everything was interwoven. When the ice-cutters came to the pond in winter in order to prepare and transport the ice to distant destinations, Thoreau thought of those who would consume it far away in the sweltering heat in Charleston or even in Bombay and Calcutta. They will ‘drink at my well’, he wrote, and the pure Walden water would be ‘mingled with the sacred waters of the Ganges’. There was no need to go on an expedition to distant countries. Why not travel at home? Thoreau noted in his journal – it didn’t matter how far one journeyed ‘but how much alive you are’. Be an explorer of ‘your own streams and oceans’, he advised, a Columbus of thoughts, and not one of trade or imperial ambitions.

Thoreau maintained as constant a dialogue with the books he read as he did with himself – always asking, prodding, niggling and questioning. When he saw a crimson cloud hanging deep over the horizon on a crisp cold winter day, he berated a part of himself that ‘You tell me it is a mass of vapor which absorbs all rays’, and then that this explanation was not good enough ‘for this red vision excites me, stirs my blood’. He was a scientist who wanted to understand the formation of clouds, but equally a poet enraptured by those billowing red mountains of the heavens.

What kind of science was this, Thoreau asked, ‘which enriches the understanding, but robs the imagination’? This was what Humboldt had written about in Cosmos. Nature, Humboldt explained, had to be described with scientific accuracy but without being ‘deprived thereby of the vivifying breath of imagination’. Knowledge did not ‘chill the feelings’ because the senses and the intellect were connected. More than any other, Thoreau followed Humboldt’s belief in the ‘deeply-seated bond’ that united knowledge and poetry. Humboldt allowed Thoreau to weave together science and imagination, the particular and the whole, the factual with the wonderful.