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Darwin and the Tree of Life: the roots of the
evolutionary tree
NILS PETTER HELLSTRO¨ M
Department for History of Science and Ideas, Uppsala University, Box 629, 75126 Uppsala, Sweden (e-mail: [email protected]).
ABSTRACT: To speak of evolutionary trees and of the Tree of Life has become routine in evolution studies, despite recurrent objections. Because it is not immediately obvious why a tree is suited to represent evolutionary history – woodland trees do not have their buds in the present and their trunks in the past, for a start – the reason why trees make sense to us is historically and culturally, not scientifically, predicated. To account for the Tree of Life, simultaneously genealogical and cosmological, we must explore the particular context in which Darwin declared the natural order to be analogous to a pedigree, and in which he communicated this vision by recourse to a tree. The name he gave his tree reveals part of the story, as before Darwin’s appropriation of it, the Tree of Life grew in Paradise at the heart of God’s creation. KEY WORDS: evolutionary theory – tree imagery – science and culture – science and religion – science and society.
INTRODUCTION
In On the origin of species, Charles Darwin (1859: 129–130) evoked an arresting image of a tree struggling with itself. The image was vivid and violent, orderly and chaotic: twigs and branches killed each other for space and survival, but simultaneously yielded beauty and “the classification of all extinct and living species in groups subordinate to groups”. Darwin’s tree, in effect, was a family tree of all life, in which the buds were individuals and the branches their ancestral lineages. “As buds give rise by growth to fresh buds”, Darwin wrote,
and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications. This peculiar tree had matured in Darwin’s mind for more than 20 years. In his notebooks on transmutation from the late 1830s, written before he developed his theory of descent by natural selection, he had invoked the Tree of Life to visualize the interconnected history and classification of living beings. From this first appearance, there existed a curious, if unstated, relationship between text and diagram; three ramifying sketches of evolutionary development followed the first mentions of the “tree of life” in the 1837 notebook (Barrett et al. 1987: 177, 180), and a branching diagram appeared shortly before the Tree of Life passage in Origin (Darwin 1859: between 116 and 117). Darwin, however, was not first to speak of the Tree of Life. Originally native to biblical Paradise, it was one of many trees that for centuries had been part of religious imagery.
Archives of natural history 39.2 (2012): 234– Edinburgh University Press DOI: 10.3366/anh.2012.
(^) The Society for the History of Natural History
www.eupjournals.com/anh
Its destiny since the appearance in Origin is fascinating: frequently employed in communication and teaching about evolution, and increasingly used as a marker of it (Hellstro¨m 2011), the Tree of Life now doubles as a “canonical icon” of evolution (Gould 1997). Gould has not been alone in accusing the tree of reinforcing hierarchy and teleology (see, for example, Deleuze and Guattari 1980: 11–37). Another challenge, perhaps more disturbing, is posed by molecular studies of prokaryote evolution. Because these indicate extensive lateral gene transfer and genes within the same lineage with different evolutionary histories, an increasing number of scientists suggest that the construction of a universal Tree of Life is rendered impossible (see, for example, Doolittle 1999, 2000, 2009, 2010; Bapteste et al. 2009; O’Malley et al. 2010; Oren and Papke 2010). Even if at the heart of criticism lies the question of why the classification and history of life necessarily should be represented by a tree^1 , then this is not to say that the tree cannot serve this purpose. It is rather to say that the reasons why it does are historically and culturally, not scientifically, predicated. So how did it happen that in 1859 a prominent British naturalist, who knew so much of real trees, included a metaphysical and metaphorical one in his groundbreaking work? And why did he name it the Tree of Life? To answer these questions, we must venture beyond natural history and inquire about Darwin’s tree in relation to extra-scientific trees and to its scriptural precursor and namesake. 2
DARWIN’S TREE
In 1837, less than a year after his return from the Beagle voyage, Darwin recorded a curious stream of thought in the first of his transmutation notebooks. Here, for the first time, he invoked the “tree of life” to account for the historical development and present distribution of species. This, to my knowledge, is the first recorded use of the Tree of Life in the context of natural history. Darwin posited a triple branching of his “tree of life” according to the elements of land, air and water, and a triple branching of each branch, as the descendant species either persisted or adapted to the other two elements. This family history explained why whales were not fish and bats not birds and why fish and penguins did not “pass into each other” (Barrett et al. 1987: 177), as they would have done in a Lamarckian evolutionary scheme, where life forms climbed the ladder of progress and every fish eventually became human. In Darwin’s view, true affinity in nature was not functional but inherited. To sharpen his metaphor, Darwin considered abandoning the tree in favour of a coral, where “passages cannot be seen” (on the “coral of life”, see Bredekamp 2005). Already in 1837, it was clear what the Tree of Life meant to Darwin; the metaphor was genealogical, developmental, adaptational and taxonomic (Barrett et al. 1987: 176–177):
Would there not be a triple branching in the tree of life owing to three elements air, land & water, & the endeavour of each typical class to extend his domain into the other domains. & subdivision three more, double arrangement. – if each Main stem of the tree is adapted for these three elements, there will be certainly points of affinity in each branch A species as soon as once formed by separation or change in part of country. repugnance to intermarriage settles it ? We need not think that fish & penguins really pass into each other. – The tree of life should perhaps be called the coral of life, base of branches dead; so that passages cannot be seen. – this again offers contradiction to constant succession of germs in progress. – [inset: no only makes it excessively complicated.]
THE TAXONOMICAL TREE
Before the end of the eighteenth century, it was not obvious that a tree was best suited to represent the order of nature. Carl Linnaeus, for example, did not invoke any tree image in his published writings, even as his fractional and hierarchical taxonomy was in harmony with the Origin diagram: the regna branched into classes, then into ordines, then into genera, and finally into species (Linnaeus 1735). But in other branches of the sciences, the tree was already the organizing principle; when Darwin appropriated the Tree of Life to visualize evolutionary classification, its biblical twin, the Tree of Knowledge, had already been used for centuries to visualize the hierarchy of learning. A passage from the account of the 1831–1836 Beagle voyage by the ship’s commander, Robert FitzRoy (1839: 658), illustrates the fluidity between science and religion during Darwin’s time:
For geology, as a useful branch of science, I have as high a respect as for any other young branch of the tree of knowledge, which has yet to undergo the trial of experience; and no doubt exists in my own breast that every such additional branch, if proved by time to be sound and healthy, will contribute its share of nourishment and vigour to the tree which sprung from an immortal root. In England, this metaphor was well-established. Francis Bacon had compared the “partitions of knowledge” to the “branches of a tree that meet in a stem” (Spedding et al. 1857: 346). Bacon did not apply the phrase Tree of Knowledge to his allegory, but he clearly related the two, remarking that “the knowledge that now is, is but a shrub, and not that tree which is never dangerous, but where it is to the purpose of knowing Good and Evil” (Spedding et al. 1857: 227). The allegory was poignantly genealogical, as in Novum organum, in 1620, he declared natural philosophy “the great mother of the sciences” (Spedding et al. 1858: 78–79). In Advancement of learning, Bacon wrote (Spedding et al. 1857: 353):
I intend Philosophia Prima, Summary Philosophy, and Metaphysic, which heretofore have been confounded as one, to be two distinct things. For the one I have made as a parent or common ancestor to all knowledge, and the other I have now brought in as a branch or descendant of Natural Science. Following Bacon, Descartes (1647) and the Encyclopaedists used tree analogies to systematize knowledge; Diderot even described the encyclopaedic vision in its entirety as a “genealogical tree” (Klapisch-Zuber 2007: 307; Ariew 1992: 101–104); his vision was rendered graphical by Chre´tien Roth in 1769 (Mouchon 1780) (Figure 1). Yet the roots of such “genealogical” trees of knowledge were even older. In 1295 the Mallorcan theologian Raymond Lull had described a taxonomic Tree of Knowledge in his Arbor scientiae. Lull’s appropriation was not as direct as may appear in translation, the Latin name for the biblical Tree of Knowledge was lignum scientiae rather than arbor scientiae, but half of Lull’s roots were divine and the name itself a close enough pun to effect the association. By virtue of Lull’s reputation and the beauty of the trees that illustrated printed editions of his book, Arbor scientiae proved one of the more significant instances of cross-fertilization between the biblical trees, ligna, and diagrammatical arbores. An arbor was a hierarchical table of the classical tradition, typically a descending schema of circles joined by lines. It organized a hierarchical and fractional universe, structured by successive subdivisions. During the Middle Ages, cross-fertilization between the biblical ligna and the diagrammatical arbor – instituted by Lull and others – made the previously sterile arbor increasingly tree-like and the distinction between arbor and ligna increasingly porous: in English as in other languages, the biblical name began to be applied
Figure 1. Chre´tien Roth’s diagram entitled “Essai d’une distribution ge´ne´alogique des sciences et des arts principaux”, produced in Weimar in 1769, which illustrated Diderot’s vision of a “genealogical tree” of all the sciences and arts (from Mouchon 1780). (Reproduced by permission of the ARTFL Encyclope´die Project, University of Chicago.)
Figure 2. Augustin Augier’s “Arbre botanique” representing the “genealogical” classification of plants from Essai d’une nouvelle classification des vegetaux (1801). (Reproduced by permission of the Bibliothe`que centrale du Muse´um national d’Histoire naturelle, Paris.)
descending lines, it more resembled the arbor porphyriana or a descending scala naturae. Even so, Lamarck (1809: 462; Voss 1952: 17) employed the received arboreal vocabulary of classification:
The following table will facilitate the understanding of what I have just set forth. One will see there that, in my opinion, the animal scale begins by at least two distinct branches, and that, in the course of its extension, several branches appear to terminate it in certain places. From this cursory inventory of trees in natural history before 1837, when Darwin first recorded his Tree of Life, three things are clear. First, arboreal and genealogical analogies were common in taxonomy. Secondly, no one before Darwin had proposed genealogy proper as the organizing principle of nature. Thirdly, no one had applied the phrase Tree of Life to a taxonomic tree. 4 Thus, although existing trees and tree-language probably contributed to and reinforced Darwin’s inclination, it is unsatisfactory to search for the roots of the Tree of Life only within natural history.
THE GENEALOGICAL TREE
In nineteenth-century Britain, trees were routinely used to visualize genealogical relations. 5 Like taxonomic trees, genealogical trees had developed from the tradition of the arbor, and more specifically from the arbor iuris and arbor consanguinitatis, both used to regulate succession and to define inbreeding, and whose graphical representation – descending schemes of names inserted into compartments – recalled trees (Watson 1934: 41–42; Klapisch-Zuber 2007: 294). Because genealogical arbores were widely circulated and enjoyed church support (Watson 1934: 42), their descending character may have contributed to reinforce and naturalize the discursive image of “descent”, as employed by Darwin in The descent of man (1871). During the Middle Ages, genealogical arbores underwent the same naturalization as other arbores; the name thus colonizing the visual expression (Klapisch-Zuber 2007: 294– 295). Instrumental in this development was the Tree of Jesse, the visual representation of Jesus’ kingly genealogy as inspired by messianic prophecy. Because the prophet described the Messiah as a flower rising from the root of Jesse, King David’s father (Isaiah 11: 1–2), the typical representation was an ascending vegetal structure connecting ancestral kings to Christ at the summit. At the apex of its popularity, in the twelfth century, the Tree of Jesse was an established theme in book illuminations and church decoration (Johnson 1961: 1; Bouquet 1996: 50; Klapisch-Zuber 2007: 295). Because the genealogical tree came from a union of the descending, ramifying and stylized arbor with the ascending, linear and vegetal Tree of Jesse, it is not surprising that many of its striking, early manifestations appeared in the religious context. One seminal appearance was in John Speed’s biblical genealogies (1611), prominently bound together with the first edition of the King James Bible and still in print during Darwin’s lifetime (for example, Speed 1817). Speed adhered for the most part to the conventions of the genealogical arbor, with descending diagrams of circled names connected by lines. Yet Noah’s genealogy was a striking exception: a naturalized tree, growing out of the ark (Figure 3). That the genealogical tree from the very beginning was applied to sacred genealogy, in a religious society, probably contributed to its long- standing impact.
In Germany, Kant followed Buffon, and Goethe followed Kant (Sloan 2006). And then, in 1809, Lamarck proposed a theory of evolution reminiscent of the evolutionary ideas expressed in 1794 by Darwin’s grandfather Erasmus Darwin in Zoonomia. But even as time and development became increasingly important, the problem that Darwin addressed in the 1830s was the same as had engaged Linnaeus a century earlier: the natural system of classification. After Linnaeus had died in 1778, the discovery of the natural order of Creation remained the main trophy of natural history and continued to motivate naturalists. In 1838, Darwin thought he had found it: “We now know what is the natural arrangement”, he declared in his “C” notebook, “it is the classification of relationship, latter word meaning descent” (Barrett et al. 1987: 286). In the 1842 and 1844 manuscripts, when he first set out to formulate his theory, Darwin made himself even clearer: “The proper arrangement of species into groups, according to the natural system, is the object of all naturalists, but scarcely two naturalists will give the same answer to the question” (Darwin 1909: 199); “... If used in simple earnestness the natural system ought to be a genealogical” (Darwin 1909: 36); “... we see that all the leading facts in the affinities and classification of organic beings can be explained on the theory of the natural system being simply a genealogical one” (Darwin 1909: 212). In Origin, Darwin (1859: 420, 422) wrote:
All the... difficulties in classification are explained... on the view that the natural system is founded on descent with modification; that the characters which naturalists consider as showing true affinity between any two or more species, are those which have been inherited from a common parent, and, in so far, all true classification is genealogical; that community of descent is the hidden bond which naturalists have been unconsciously seeking... The reader will best understand what is meant, if he will take the trouble of referring to the diagram in the fourth chapter.... the natural system is genealogical in its arrangement, like a pedigree. Darwin’s theory proposed to solve Linnaeus’s problem by recourse to genealogy. The suitable model for genealogy was the tree. Earlier “genealogical trees” in taxonomy and natural history, together with the established habit of describing relations in nature in arboreal, genealogical terms, most probably contributed, but, importantly, no earlier taxonomy had been properly genealogical, showing common descent. Whereas genealogy had been an allegory to earlier naturalists, Darwin understood the allegory literally; his contribution, in a sense, was therefore to think the metaphor to its end. But why was he first to do so? Or, to speak with Hacking (2007: 221): “Why did we have to wait until Darwin before it became obvious that the classification of living things should be presented as a tree?” The answer could perhaps be approximated through Darwin’s family history. The Darwins and Wedgwoods were wealthy and well known, conscious and proud of their history and importance. Darwin’s sense of stemming from an “ancient” and “august” family is manifest in an 1839 letter to his second cousin William Darwin Fox. In the letter Darwin also expressed a particular sense of inherited rights to the vocation of naturalist. He may have been joking, but it was no isolated expression: two years earlier, Darwin had written “Zoonomia” at the head of his first transmutation notebook (Barrett et al. 1987: 170), the title of his grandfather’s great treatise:
Talking of family affairs, can you tell me from memory what the motto to our crest is for I mean to have a seal solemnly engraved... it was aude? et –?... When at Shrewsbury I had a regular hunt through some old papers & pedigrees relating to our most ancient family, which as you say is older than the heralds office... The pedigrees want filling up terribly; so ancient a family ought not to be neglected... By the way Hensleigh Wedgwood made a curious discovery regarding our august family, which I must tell you, that a W. Darwin my
great grandfather is described in the Phil. Transacts for 1719, as a person of curiosity, who discovered the remains of a giant, evidently an Icthyosaurus. – so that we have a right of hereditary descent to be naturalists & especially geologists. 6 It is well known how Darwin’s naturalist grandfather inspired him on the unity and evolution of organic life, having proposed that life originated from one or two “filaments”, differences of type resulting from subsequent change (Darwin 1794:500). Less well known is the way Darwin adopted his grandfather’s peculiar view of trees, as compounds of individuals rather than as contained organisms (Darwin 1794: 102):
The individuals of the vegetable world may be considered as inferior or less perfect animal; a tree is a congeries of many living buds, and in this respect resembles the branches of coralline, which are a congeries of a multitude of animals. Each of these buds of a tree has its proper leaves or petals for lungs, produces its viviparous or its oviparous offspring in buds or seeds; has its own roots, which extending down the stem of the tree are interwoven with the roots of the other buds. Clearly influenced by his grandfather, Darwin noted in 1838 that “my pleasure in Kensington Gardens has often been greatly excited by looking at trees as great compound animals united by wonderful & mysterious manner” (Barrett et al. 1987: 529), and in 1844 he declared that “It is very doubtful whether the flowers and leaf-buds, annually produced from the same bulb, root, or tree, can properly be considered as parts of the same individual” (Darwin 1909: 58). 7 Darwin’s understanding of trees may have reinforced his idea of a genealogical tree, even as the organization of real trees may have appeared to coincide with that of the metaphysical. Darwin’s interest in animal breeding and domestication may also have reinforced his preoccupation with pedigrees and genealogy. This interest was not limited to the naturalist period of his life or to pigeons (see Secord 1981). As a child, Darwin grew up in agricultural Shropshire, and from an early age, he loved hunting; a sport where not only the hunting gentlemen but also their horses and dogs had pedigrees. After Darwin had been offered a place on board the Beagle in 1831, it was as a young country gentleman he wrote to his mentor Henslow that “till one to day I was building castles in the air about hunting Foxes in Shropshire, now Lamas in S America”. 8 A passage from Origin would sum up Darwin’s upper-class world, where the place of an individual was dictated by blood, and where greyhounds and racehorses came to mind when discussing functionally similar but biologically unrelated animals (Darwin 1859: 427):
The resemblance of the greyhound and race-horse is hardly more fanciful than the analogies which have been drawn by some authors between very distinct animals... For animals, belonging to two most distinct lines of descent, may readily become adapted to similar conditions, and thus assume a close external resemblance; but such resemblances will not reveal – will rather tend to conceal their blood-relationship to their proper lines of descent. Darwin (1859: 431) himself related his proposed natural system to the family trees of the privileged classes, comparing the difficulty of establishing relations in nature to the difficulty “to show the blood-relationship between the numerous kindred of any ancient and noble family, even by the aid of a genealogical tree”. But the tree was threatening to undermine the aristocratic world view even as it came from it. When Darwin wrote of “a single progenitor” (Darwin 1859: 413) or the “one primordial form” (Darwin 1859: 484), his theory seemed to threaten not only the select character of the wealthy and the white, but also of humanity. “Our ancestor”, wrote Darwin in a letter to Lyell, in 1860, “was an animal which breathed water, had a swim-bladder, a great swimming tail, an imperfect skull, and undoubtedly was an hermaphrodite!
tablets (James 1966: 68–70, 1968: 241–242), and the concept may well precede writing. The phrase Tree of Life came to English with the translation of the Bible, where it appeared in prominent first and last place positions. In the primordial Paradise described in Genesis, Adam and Eve ate from the Tree of Knowledge and thus lost the Tree of Life (Genesis 2: 9; 3: 22–24). In the future Paradise envisioned in Revelations, the Tree of Life will again stand at the centre of existence (Revelations 2: 7; 22: 2). The Tree of Life also figures in the Bible as an allegorical image of regeneration, vitality and prosperity (Proverbs 3: 18; 11: 30; 13: 12; 15: 4; II Esdras 2: 12; 8: 52). In this derived sense, the Tree of Life remained important to Christian discourse well into Darwin’s time, as is clear from its recurrence in the titles of spiritual publications throughout the nineteenth century.^10 During the Middle Ages, another layer of meaning was added to the Tree of Life, as theologians proclaimed the symmetry between the first Adam, who brought death into the world, and the second, who redeemed humanity on a cross crafted from Edenic wood. Through such teleologies, Christ became the Tree of Life incarnated, a promise of regeneration and deliverance from death (Schama 2004: 219–220; James 1968: 244–245). In its biblical sense, the Tree of Life was still a common metaphor in Darwin’s time, both in religious and artistic imagery. Often it appeared in opposition to the Tree of Knowledge. In the early nineteenth century Byron (1817: 7) declared that “The Tree of Knowledge is not that of Life”, while Goethe (1808: 124; 1833: 70) wrote that “Grey, my dear friend, is all theory, and green the golden tree of life”. Darwin must have come across such references, yet his relationship to the trees of God was more intimate than that: he had brought them with him onboard the Beagle. Beer (2009: 27) has argued that Darwin’s early reading influenced his imaginative development. In particular, she has drawn attention to “The intimacy and solitariness of his contact with Milton” (Beer 1985: 549; 2009: 27). In his autobiography, Darwin himself recalled that: “Up to the age of thirty, or beyond it, poetry of many kinds, such as the works of Milton, Gray, Byron, Wordsworth, Cole-ridge, & Shelley, gave me great pleasure” (Darwin 1887: 1 : 100). “Milton’s Paradise Lost had been my chief favourite, & in my excursions during the voyage of the Beagle, when I could take only a single small volume, I always chose Milton” (Darwin 1887: 1 : 69). Darwin literally carried Milton’s retelling of Genesis around the world. In Paradise lost the tree theme was even more emphatic than in the Biblical original: the Tree of Knowledge appeared in the second line and the poet repeatedly returned also to the Tree of Life, “the middle Tree and highest” (Milton 1674: 4 : 193). 11 Throughout the poem, Milton sustained a tension between Life and Knowledge, as in the following passage (Milton 1674: 4 : 214–219):
Out of the fertil ground he caus’d to grow All Trees of noblest kind for sight, smell, taste; And all amid them stood the Tree of Life, High eminent, blooming Ambrosial Fruit Of vegetable Gold; and next to Life Our Death the Tree of Knowledge grew fast by. It is clear from records that Paradise lost remained in Darwin’s mind throughout his voyage and life. In an 1832 notebook entry from Chile, Darwin compared the ocean to the infernal regions of chaos (Keynes 1988: 111), in a letter to Henslow in the same year
he described a toad with reference to Milton’s Satan^12 , and in a note from 1835 he reminded himself to bring along Milton’s book (Chancellor and van Wyhe 2009: 480). In The expression of the emotions in man and animal, Darwin (1872: 304–305) still referred to Milton. Even as he sat down to write his autobiography, Paradise lost came to his mind, now as the privileged reference for Creation, even before the Bible (Darwin 1887: 2 : 187):
I find no difficulty in imagining that, at some former period, this universe was not in existence; and that it made its appearance in six days (or instantaneously, if that is preferred), in consequence of the volition of some pre- existent Being... I had not then, and I have not now, the smallest a priori objection to raise to the account of the creation of animals and plants given in ‘Paradise Lost,’ in which Milton so vividly embodies the natural sense of Genesis. In the nineteenth century, scientific works drew on literature, and vice versa, so that “metaphors, myths and narrative patterns could move rapidly and freely to and fro between scientists and non-scientists” (Beer 2009: 5). Darwin’s Cambridge patron Adam Sedgwick, for example, used to quote Milton at length (Barrett 1974: 149), and Lyell referred to Paradise lost in Principles of geology (Lyell 1830: 37, 431; 1832: 135; 1833: 89). Onboard HMS Beagle, Darwin read Lyell’s geology along with Milton’s poetry (Burkhardt and Smith 1985: 562–563). Milton’s vivid account of Creation, with the centrality it accorded to the Tree of Life, impressed the young Darwin, who read descriptions of Paradise in paradisiacal places: “Epithet after epithet was found too weak to convey to those who have not visited the intertropical regions, the sensation of delight which the mind experiences”, Darwin (1839: 591) concluded. He described trees as others describe humans: they were “noble” and “remarkable”, “beautiful” and “handsome”, sometimes “curious” and “ugly”, “fine” or “stately” (Darwin 1839: 10, 24, 28, 36, 80, 312, 316). “In my last walk”, Darwin (1839: 591) wrote, “I stopped again and again to gaze on these beauties, and endeavoured to fix for ever in my mind an impression, which at the time I knew, sooner or later must fail.” Darwin travelled on the Beagle from 1831 to 1836. Upon returning to England, in 1837, there appeared the first record of the Tree of Life in his notes. That Darwin knew well whence he took the name for his tree is beyond doubt. Still, there may have been other influences that helped shape it. In March 1841, Darwin read a newly published book, Heroes, hero-worship, and the heroic in history, by Thomas Carlyle, a family acquaintance. 13 Carlyle’s book included a striking description of the “old Norse view of Nature”, imagined as the cosmic ash-tree Yggdrasil. Darwin had only known Carlyle personally since 1838, so the poet cannot have influenced him in 1837. Yet, Carlyle’s Yggdrasil may have influenced the Tree of Life as it was presented in Origin. Notice how Carlyle’s Tree of Existence gathers “All Life”, the boughs being nations and “every leaf of it a biography”; notice also how it is described as a “view of Nature”, and how, as later in Darwin, the tree is “beautiful and great” (Carlyle 1841: 32–33):
I like, too, that representation they have of the Tree Igdrasil. All Life is figured by them as a Tree. Igdrasil, the Ash-tree of Existence, has its roots deep down in the kingdoms of Hela or Death; its trunk reaches up heaven- high, spreads its boughs over the whole Universe: it is the Tree of Existence. At the foot of it, in the Death- kingdom, sit Three Nornas, Fates, – the Past, Present, Future; watering its roots from the Sacred Well. Its ‘boughs,’ with their buddings and disleafings, – events, things suffered, things done, catastrophes, – stretch through all lands and times. Is not every leaf of it a biography, every fibre there an act or word? Its boughs are
ACKNOWLEDGMENTS
I thank James Moore, Gillian Beer, Anne Secord, James Secord, Eleanor Robson, Jesse Olszynko-Gryn, Jenny Bangham, Adrian Desmond, Christiane Klapisch-Zuber, David Feller, Doina-Cristina Rusu, Maggie Barker, Sophie Jouffreau, and an anonymous referee.
NOTES
(^1) Darwin also considered the “coral of life” (Barrett et al. 1987: 177) and spoke of a “web of affinities” (Darwin 1859: 434). (^2) Beer (2009: 32–33, 86) is acknowledged for mentioning the biblical tree. (^3) C. Darwin to A. Gray, 5 September 1857 (Burkhardt and Smith 1990: 449). (^4) For the history of trees in natural history, see Voss (1952) and Ragan (2009). (^5) The Oxford English dictionary reports the use of arboreal language for genealogy since the Middle Ages. (^6) C. Darwin to W. Darwin Fox, 24 October 1839 (Burkhardt and Smith 1986: 234–235). (^7) Darwin (1839: 261–262) also repeated his grandfather’s comparison between coralline and trees. (^8) C. Darwin to J. S. Henslow, 5 September 1831 (Burkhardt and Smith 1985: 142). (^9) C. Darwin to C. Lyell, 10 January 1860 (Burkhardt et al. 1993: 29). (^10) See for example Kennedy (1854), Cumming (1857), Smith (1860) and Shepheard (1864). (^11) It is not established which edition Darwin carried; hence all references to the first complete edition of 1674. (^12) C. Darwin to J. S. Henslow, 24 Nov 1832 (Burkhardt and Smith 1985: 280). The toad also made it into Researches (Darwin 1839: 114–115); see Milton (1674: 4 : 798). (^13) Darwin’s brother Erasmus introduced them to each other over tea in 1838. Darwin read all of Carlyle’s works. In a letter from 1840 Darwin’s wife Emma wrote: “I have been reading Carlyle, like all the rest of the world... Charles keeps on reading and abusing him” (Litchfield 1915: 52). In his “Books read” notebook, Darwin judged Hero-worship to be of “moderate” quality (Burkhardt and Smith 1988: 462). (^14) “His mind seemed to me a very narrow one”, wrote Darwin (1887: 1 : 78) about Carlyle, “even if all branches of science, which he despised, were excluded” (note the tree reference). (^15) A. Einstein to Kamerlingh-Onnes’s widow, 25 February 1926; Einstein Archive 14–389.
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Received 1 July 2011. Accepted 16 December 2011.
