No single set of letters was more important to Darwin than those exchanged with his closest friend, the botanist Joseph Dalton Hooker.

The 1400 letters exchanged between Darwin and Joseph Dalton Hooker (1817-1911) account for around 10% of Darwin’s surviving correspondence and provide a structure within which all the other letters can be explored.  They are a connecting thread that spans forty years of Darwin’s mature working life from 1843 until his death in 1882 and bring into sharp focus every aspect of Darwin’s scientific work throughout that period. They illuminate the mutual friendships he and Hooker shared with other scientists, but they also provide a window of unparalleled intimacy into the personal lives of the two men. 

Their correspondence began in 1843 when Hooker, just returned from James Clark Ross’s Antarctic expedition, and already an admirer of the older man, was approached about working on Darwin’s collection of plants from the Beagle voyage. Just the previous year Darwin had written out his first coherent account of the main elements of his species theory, and within a few months Hooker was admitted into the small and select group of those with whom Darwin felt able to discuss his emerging ideas. In perhaps his most famous letter of all, Darwin wrote to Hooker in January 1844 of his growing conviction that species “are not … immutable” – an admission he likened, half jokingly, to “confessing a murder”. When Alfred Russel Wallace (1823-1913) sent Darwin a letter in 1858 outlining an almost identical theory to his own, it was Hooker, together with Charles Lyell, who engineered the simultaneous publication of papers by both men, and secured Darwin’s claim to the theory of “modification through descent” by means of the mechanism Darwin called “natural selection”.

It was also to Hooker that Darwin, writing furiously in the succeeding months, sent batches of the manuscript of On the Origin of Species for comment, and Hooker continued to be a sounding board for successive publications.

Much of the most important experimental work conducted by Darwin after the publication of Origin was on variation and adaptation in plants, in particular the mechanisms by which various plants are nourished, reproduce, and colonise. Hooker, who after ten years as assistant director of the Royal Botanic Gardens, Kew, succeeded his father as director in 1865, was perfectly placed to provide Darwin with exotic species, and to help him build vital global networks of well-informed correspondents.

Hooker was a frequent visitor to Darwin at his home in Downe, Kent, and became a great favourite of Darwin’s children. The two men shared their experience of attending the birth of their children: Darwin advocated the use of chloroform which he thought as “composing to oneself as well as to the patient”. It was to Darwin that Hooker wrote just an hour after the death of his six year-old daughter, Maria, knowing that his friend, who had lost both a ten year-old daughter and a baby son, would all too clearly understand his grief. Those letters are amongst the most poignant in the collection.

Of the many hundreds of letters that passed between Darwin and Hooker all but a handful of those that survive are in the Cambridge Darwin archive. Darwin’s son Francis incorporated many extracts in two published editions of his father’s letters, in 1888 and 1902, the second of which he dedicated to Hooker “in remembrance of his lifelong friendship with Charles Darwin”. At some time between those two editions, Hooker returned Darwin’s letters to the family, retaining copies for himself; those copies now form part of the Hooker archive at the Royal Botanic Gardens, Kew. Both sides of the original correspondence, bound into several large volumes, arrived in Cambridge University Library, in 1948, together with the bulk of the Darwin archive, following transfer of ownership from the Darwin family, supported by funding from The Pilgrim Trust.

Being able to see the original letters complements the transcriptions and contextual notes. An original can reveal the state of mind of the writer, in particular anxiety or agitation (as in the letter about the death of baby Charles for example with enlarged, untidy writing and deletions), or uncertainty.  And they can capture the formality or informality of their relationship with the recipient. 

The use Darwin made of the information in letters is also obvious, for example in his annotations to Hooker’s comments on the first edition of Origin, which he also methodically crossed through as he used them to revise the later editions.

And letters written in pencil suggest Darwin was unwell – you can’t use an ink dip pen lying down. 

Key letters

Developing a theory:

Darwin to J. D. Hooker, [11 January 1844]: Darwin cautiously reveals to Hooker, who he has only been corresponding with for a few months, his conclusion that species are not immutable. It is, he says, “like confessing a murder”.

Going public:

On 28 June 1858, just a few days after Darwin received Alfred Russel Wallace‘s essay outlining the same mechanism for species change as his own, Darwin’s baby son, Charles Waring Darwin, died of scarlet fever.  The following day, distracted by grief, Darwin sent two letters to Hooker who was in the midst of arranging for Darwin’s work on species change to be read at a meeting of the Linnean Society together with Wallace’s, and thus to secure Darwin’s claim as originator of the theory of natural selection. “It is miserable in me” Darwin wrote in his second letter “to care at all about priority”.

The writing of Origin and its reception:

Hooker was one of the few to whom Darwin sent manuscript of On the Origin of Species for comment – with close to disastrous results when Hooker’s children used some of it for scrap paper.    Darwin wrote to Hooker in triumph once it was finished, “You cannot think how refreshing it is to idle away whole day, & hardly ever think in the least about my confounded Book, which half killed me”, and indignantly about the response of the old fogies of Cambridge. 

Read Hooker’s description of the famous 1860 Oxford meeting of the British Association for the Advancement of Science when the Bishop of Oxford denounced the ideas in Origin,  and Darwin’s delighted response.

Darwin later regretted using the word “creation” in the second edition of Origin.

Friendship, gossip, and shared jokes:

Hooker started a running joke in their correspondence about the British aristrocracy being the result of natural selection. 

When Hooker had his family silver stolen by a man who had chatted up his maidservants, he asked the Darwins to recommend an old and unattractive cook.  Darwin replied that he wished natural selection had resulted in neuter humans who would not flirt.

Hooker suggested they should give up science and just write gossip. There is a good example in a letter in which Darwin speculates that a lady of their acquaintance might be an illegitimate daughter of his grandfather, Erasmus Darwin.

Hooker sometimes made fun of Darwin’s appearance: he addressed one letter to his “Glorified Friend” after receiving a photograph of Darwin that reminded him of an image of Moses.

Fatherhood:

(Fanny has just had a fine boy, excuse the interruption)

On attending the births of their children, when both men administered chloroform to their wives (see letters 1573 and 1576).  The birth of one of Hooker’s sons interrupted the writing of one letter, and Darwin teased him for reporting it so casually.

Grief and loss:

Both men also lost children.  Hooker wrote to Darwin within an hour of the death of his six year old daughter.    And it was to Hooker that Darwin expressed his grief at the loss of his daughter-in-law, Amy, who died in childbirth.

Novels and politics:

The two families shared their views on literature and often recommended books to oneanother, and commented on the politics of the day. 

Hooker and Darwin had rather different attitudes to the American Civil War.  Hooker took a hardline view on protecting British economic interests and fell out with their mutual friend, the Harvard botanist Asa Gray (see for example letter 3395); Darwin’s views were chiefly coloured by his staunch opposition to slavery.   The letter in which Darwin discusses this most openly also demonstrates how completely entwined the public, scientific, and personal are in their letters: it also continues the joke about the aristocracy, is rude about Darwin’s one-time friend and bitter opponent, the palaeontologist Richard Owen, and contains Darwin’s completely accurate prediction that there must be a moth with an exceptionally large proboscis as the necessary pollinator of the recently discovered orchid Angraecum sesquipedale.

Hooker on travel:

Hooker’s descriptions of trekking in India are in his archive at The Royal Botanic Gardens, Kew (see letters 1247 and 1319), but you can read Darwin’s reaction on hearing Hooker had been imprisoned in Sikkim, and Hooker’s comparison of the Himalayas and the Swiss alps.