The Vegetal and the Manifold: Agnes Arber’s Botanical Panentheism

“This type of thought cannot be tied down to a clear-cut prearranged programme; we have to leave it free to grow untrammelled, under our hands.” 

—Agnes Arber, The Manifold and the One¹

Just three years before her death, in a move that surprised many but not those who knew her, the Cambridge, England–based botanist, plant morphologist, and philosopher Agnes Arber (1879–1960) published a book enamored with contemplative mystics, ecstasy, and negative theology.² In that mystical theological tradition, contradictions abound. What cannot be said about ultimate reality carries as much weight as what can. The Manifold and the One revels in the complexities of the unknown. 

Reception of the book ranged from circumspect distance to less-than-respectful silence. Some feared that Arber had abandoned botany “for the darkling universe of epistemology.”³ And so, even while current academic turns to feminist science studies (particularly reclaiming the history of women in science) and critical plant studies surface Agnes Arber’s scholarship as a vital “voice of dissent from the Western tradition’s devaluation of plants,”⁴ the silence on her last book lingers. Most recent research on Arber ignores Manifold or positions that final book as a strange and irrelevant diversion.⁵

The American plant biologist Maura Flannery observes that “The Manifold and the One is [Arber’s] only book that does not deal specifically with botany: instead, it is a philosophical and historical exploration of the idea of the relationship between unity and diversity.” However, Flannery continues, “While this book is dismissed by her Royal Society biographer, H. Hamshaw Thomas, in a single sentence as a ‘philosophical essay’ . . . it tells a great deal about her thinking and thus throws light on the rest of her writings.”⁶ With that provocation from Flannery, I wish to reclaim The Manifold and the One as crucial for Arber; her final book might be read as philosophical botany growing wild. Hers is a panentheistic vision of reality that is irreducibly shaped by a view of the complexity of plant life and form with a deconstructive edge. That vision is defined by a contemplative approach to botany, a unique and nonlinear appreciation rooted in plants for the multiplicity of the world, and, finally, an extension of that appreciation to a mystical appreciation of metaphysics.

Early works such as Herbals (1912), Water Plants (1920), Monocotyledons (1925), and The Graminae (1934), established Arber’s singular style through her careful morphological description and compelling botanical sketches. Even so, she researched and wrote with little institutional support and irregular access to laboratory space. As Kathryn Packer notes, “Arber's work was largely unfunded as she did not have a permanent paid position, and neither did she receive much funding through research grants.”⁷ After being displaced from the Balfour Laboratory at Newnham College, Cambridge, Arber set up a laboratory in her home while raising her daughter, Muriel. And when World War II made sourcing research materials difficult, Arber turned to more philosophical approaches.⁸

Arber’s books in the 1950s exemplify this turn. The Natural Philosophy of Plant Form (1950) collects the history of plant philosophy and places that tradition within the context of her research in botanical morphology. The Mind and the Eye (1954) serves as a manual for biologists but expands the approach of biological research to include philosophical traditions. And, as we’ve noted, The Manifold and the One (1957) considers questions of divinity, mysticism, and ultimate reality.

In Manifold, Arber incorporates a wide variety of religious and philosophical sources ranging from Christian theology (e.g., Pseudo-Dionysius, Eriugena, Nicholas of Cusa, Julian of Norwich) to Islamic mysticism (Al-Ghazali, Rumi) and Hinduism (the Bhagavad Gita) to sources in poetry and literature such as Dante, Milton, and Blake. Her writing explores a polydox interest in how religious traditions have historically engaged the question of the unity and multiplicity of reality.⁹ Arber herself notes that this question informs her earlier work, writing, “Year after year the mystery of Unity and the Manifold has held its place in the background of my mind, gradually becoming so insistent that I was impelled irresistibly to try to approach it on various lines.”¹⁰

The first half of Manifold reflects on contemplation as an approach to thinking mystically and philosophically about the unity and multiplicity of reality. Mysticism opens up a broader view of seeing reality; the practice of contemplation gathers a sense of seeing both the multiplicity and the unity of reality together while navigating the capaciousness of that seeing. Here, Arber invokes Greek philosophy’s interpretation of theory as “beholding.” Theory, she observes, “may be translated in some contexts as ‘contemplative seeing’. It thus refers to a type of thought synthesizing the intellectual and visual powers.”¹¹

Arber’s recommendation of an open, contemplative engagement with reality emerges from her botanical attention. The Natural Philosophy instructed a scientific-philosophical observation of plant morphology by applying the classical Greek method of theory as beholding:

This may well be one of the reasons why the study of plant form was initiated and carried to so advanced a point in the classical period, for the visual capacity of the Greeks reached a peculiarly high level. It is not mere chance that in their language the words for “knowing” (εἰδέναι) and “seeing” (ἰδεῖν) came from the same stem, and that one term, θεωρία, was used both for scientific investigation and also for beholding. The Greeks understood how to think with the mind’s eye.¹²

Arber drew inspiration from the Greek perspective to pay attention to plant form. Taking plants seriously means beholding plants in their living dynamism.

Yet Arber does not conflate the roles of scientist and contemplative mystic with regard to theory. She contrasts their relations with how they use words: Science is expounded in public while mystical experience privately reaches for the limits of communication.¹³ Arber notes that mysticism pulses from its own botanical ground, explaining, “The more pedestrian levels of existence are necessary as the soil out of which the ultimate mystical state can flower and to which its seed-harvest must return.”¹⁴ Arber’s own practice is rooted in seeing plants, and not just metaphorically.

One could mistake Arber’s contemplative practice as anthropocentric imagination, an assuming that humans oversee and order the world. But Arber refuses that characterization: “Another factor which cramps the biologist’s visual thinking,” she writes, “is his tendency to share the general egoism which leads to concentration on the human element in the universe, so that when he looks at an animal or plant he is liable to see it, not as it is in and for itself, but from an anthropocentric standpoint.”¹⁵ Morphology is a contemplative practice of challenging anthropocentrism in all of its guises. What emerges from it is the being’s own peculiarity. 

Instead of mere observation or constructing an idealistic state, Arber’s contemplation envisioned the dynamism of living and dying. “To study morphology is to see through the changing forms and the parts, to the living processes and the whole,” the environmental philosopher Isis Brook has written about Arber. “This requires a way of observing and of thinking that does not make hard and fast distinctions.”¹⁶ As Arber expounds in The Natural Philosophy of Plant Form, contemplation brings together a number of ways of “seeing through.” She recommends three interrelated steps: (1) seeing the plant with “sensuous perception,” (2) filling out a mental picture of the plant, and (3) going beyond that static image to “see it in its living aspect, and in relation to other forms.”¹⁷ A living aspect is constantly undoing any static or essential form. 

The philosopher Stella Sandford notes that “[Arber] looked back to Aristotle’s concept of form (eidos), which she understood to refer to the ‘intrinsic nature of which any given individual was a manifestation.’ Going considerably beyond Aristotle, she took this ‘intrinsic nature’ to encompass the entire life-history of a plant, including changes in the size and outward shape of the plant, thus redefining form as dynamic and refusing to separate it analytically from function.”¹⁸ The “living aspect,” the dynamism of the process of plants, expands the philosophical view, and the relational context of vegetal life undoes an overdetermined mental image of the plant. Arber destabilizes the botanist’s habit to overdetermine form. 

Here, contemplation makes room for living interactions and indeterminacies. The contemplation of plants entails its own unravelling of images and pictures of settled vegetal form.¹⁹ Anything that might be captured in a particular moment in time might be unsettled, and so carries the possibility of its own undoing. 

Negative theology follows this contemplative pathway as well, giving particular attention to the infinite, where anything that can be said about the Divine resists totality and must be unsaid. As Michael A. Sells notes of negative theology, “Each statement I make—positive or ‘negative’—reveals itself as in need of correction. The correcting statement must then itself be corrected, ad infinitum. The authentic subject of discourse slips continually back beyond each effort to name it or even to deny its nameability.”²⁰ Plants similarly risk undoing not just the articulation of their assumed forms, but static views of thinking.²¹ Just as the contemplative seeks an encounter with mystery, Arber discovers mystery in and as vegetal indeterminacy.

Arber’s fuzzy, negative morphology loops back into a fuzzy engagement with metaphysics. As Brook observes, “The sense of a plant’s striving that runs through Arber’s work helps to redefine morphology. . . . Fuzzy Arberian Morphology paved the way for process morphology, whose point is to analyse and describe the dynamic continuum of plant form, no longer describing the structure of a plant and its processes as separate.”²² The unity and multiplicity of reality is impossible to nail down. 

Contemplating the living relations and multiplicity of reality means that we must not only chasten our anthropocentric approaches to plants, but also challenge hierarchies and too-certain thinking-systems that do not take plant life seriously. Arber begins Manifold by rejecting hierarchies, particularly that of the anthropocentric “Great Chain of Being”: “All modern biologists, widely as they may differ among themselves in other respects,” she writes, “agree in rejecting this picture of a single ladder-like sequence of living things; the oak tree, for instance, has an individualised ‘oak-tree-ness’ which is the consummation of its self-expression.”²³ Arber’s own sense of form requires that the particularity of living things, especially plant life, all hold their own in the question of the Manifold and the One. The oak lives not on a hierarchical plane of reality but with its own vitality in the midst of other living things.

This challenges the confines of flattened or imposed boundaries of logic. Arber again: 

I soon found that in trying to think about the nature and the relations of the One and the Many the simple linear type of thought and argument, which is used in dealing with scientific problems, does not suffice. We can no longer depend exclusively upon straightforward sequences from premises to conclusions by means of orthodox logical thinking.²⁴

Thought grows wild, out of bounds, “untrammelled.” But for Arber even the research of plant and other biological science emerges nonlinearly. In The Mind and the Eye, she argues, “The experience of one’s own thinking suggests that it moves, actually, in a reticulum (possibly of several dimensions), rather than along a single line.” She refers to thinking as a river “which includes eddies and still backwaters.”²⁵ Biologically, a reticulum is a network or net. Plant cells synthesize proteins to build cell walls for photosynthesis. Thinking similarly grows across chambers or “dimensions,” transforming, cross-pollinating, stretching, blossoming, and recoiling in unexpected ways. 

The living aspect of thinking upends the linearity of thought, but contemplation also opens a mystical sense of seeing the world where contradictory experiences of reality collect and coincide. A number of these contradictions in mysticism hold together for Arber. Unity and diversity exist alongside each other, for instance. Reason and sense, too. Transcendence and immanence coincide. The individual coincides with the “suprapersonal.” Thought’s reticulum abides contradiction. 

To articulate the reticulate, Arber deploys the negative theological concept of the “coincidence of contraries,” which is associated with the 15^th-century theologian Nicholas of Cusa. Cusanus’s understanding of “learned ignorance” and his coincidentia oppositorum proposal paradigmatically embody approaches for a speculative mysticism like Arber’s.²⁶ We are constantly learning limits—not just the limits of our knowing, but also of our previously held certainties. All contradictions, for Cusanus, coincide in God or ultimate reality, but the term might also name the logically murky space of everyday experience where metaphysical categories fall apart.²⁷

Arber returns to Cusanus time again to articulate the mutually indwelling categories that orient her study of the mystics. The interaction of linear and nonlinear “reticulate” thinking creates space to hold contraries together. “Perhaps [the coincidence of contraries] is best explained,” Arber writes, “by saying that in general it involves getting beyond the Law of Contradiction, which is the basis of all ordinary discursive-logical reasoning. This Law as we have already noticed may be epitomised roughly as A is not both A and not-A; its corollary the Law of Excluded Middle (A is either B or not-B) implies that between contradictories there can be no mediating term.”²⁸ Dominant modes of logic bifurcate reality into discrete categories, but the nonlinearity of thinking and the living processes of life upend ordinary discursive reasoning.

What is remarkable in Arber’s engagement with Cusanus is that she explicitly returns to botany to apply this feature of negative theological and mystical thought. Just as much as we encounter limits in thinking ultimate reality, so too do the everyday ways we bifurcate, classify, and taxonomize living categories fall apart. 

That this idea of unmediated opposites is a crude one may be illustrated from the study of the classification of living beings. … A student at the text-book stage might say glibly that monocotyledons can be distinguished from the dicotyledons by having the parts of their flowers in threes; but in actual fact this trimery is by no means universal in monocotyledons, while it is sometimes to be found in dicotyledons.²⁹

The categories meant to organize scientific classification break down in their living dynamics since they hold contradictions in their logic. For Arber, this means we navigate these contradictions by the stress or accent and minimization by “relative emphasis.”³⁰ Vegetal being exposes the inadequacies of logic and taxonomy. Living entities encourage a collapse of our logic and thinking that dances, out of step, around the edges of thought. Vegetal life grows through the cracks of our everyday assumptions, and affords us the possibility to behold more honestly.

We might now ask: where do botany and vegetality sit within traditional theological logic? The logic of the One has held claim over so much of what Banu Subramaniam calls the “coloniality of botany.”³¹ Arber’s scholarship, in its positioning of sources, in its history of taxonomy, and in its categorical morphology, is not exempt from this enterprise. And in another sense, her collecting of global religious sources in Manifold could be said to seek a dangerous totality. More radically, though, her curiosity and reverence for the multiplicity of traditions and thinkers opened her thinking. Seen alongside the One, multiplicity unsettles the established categories of morphology and linear thought.

In pursuing the nonlinear and contradictory, Arber’s project resists the sublimation of the Many to the One. She acknowledges the fragility of her scientific categories and the danger of anthropocentric thinking.³² The multiplicity of the world, plants and all, does not dissolve into mystical union with the One but affirms it. The temporal and eternal “interweave.” Transcendence does not overtake immanence—both are affirmed. Finitude gives character to infinity, and vice versa.

Like a flower folding and unfolding in response to sunlight, the pulses of unity and multiplicity might offer a kind of synthesis and interactivity. Arber writes,

The processes of transition from the One to the Many, and from the Many to the One, are thus seen in the organism as alternating sequences, strung out in time. Can it be that it is in this to and fro relation between the One and the Many that the very essence of livingness is revealed? Life would then be neither Unity alone, nor the Manifold alone, but would be visualised as their joint expression, in which predominance is accorded to each in turn, in a constant rhythm.³³

The cover designs on multiple editions of Manifold depict a kind of floral geometry, a pulsing reality enfolding and unfolding coincidences of contraries.

Rather than lose herself to an absolute transcendence or pure immanence, then, Arber opts for a philosophical panentheism: the One in all and all in the One.³⁴ She sees the One and Many in each other, folding and unfolding, petal by petal. Her botanical imagination carries her to the end in this odd, often discarded text. This matters significantly for Arber’s legacy. As she concludes the book, “If the light is sufficient to disclose to us the way of contemplation that lies within ourselves, we may by pursuing it to the end come to know—not as a mere static dictum but as a winged intuition, carrying an infinitude of significance for both mind and heart—that the One is the Manifold, and the Manifold is the One.”³⁵ Both trajectories are true simultaneously, indwelling each other—all in all—without one obliterating the other. 

Multiplicity is too often mistaken for imprecision at best, or a naïve ecological “harmony” at worst. Philosopher Michael Marder argues, however, that body and soul, “self and other, depth and surface, life and death, the one and the many, and so forth,”—so many “metaphysical separations”—are “practically deconstructed in vegetal existence.”³⁶ What instead would it be like to envision Arber’s reflection on the “Many and the One” as performing and providing for an extended vegetal deconstruction of this very metaphysical separation? Plants are many and one simultaneously, folding and unfolding, in a process of becoming from moment to moment. Arber’s final work unleashes an eclectic florilegium of the Divine. 

Manifold collects and gathers winding and living movements in apophatic theology, compiling Arber’s botanical insights into a robust vision of the mysteriousness of the world. In doing so, it resists the bifurcation of thought in and of botanical and theological imagination. As Sells writes, “At its most intense, apophatic language has as a subject neither divine nor human, neither self nor other. It can be read as a relentless critique of religious traditions or as a realization of the deeper wisdom within such traditions. It can be read as grounded in the intimate specificities of particular traditions or as opening onto intercultural and inter-religious conversation. These possibilities may not be mutually exclusive.” ³⁷ Considered in light of negative theology, Arber invites a conversation on interrelational metaphysics, divinity and world pulsing together, opening multiplicities and coincidences from the finite to the infinite and back again.

¹ Agnes Arber, The Manifold and the One (John Murray, 1957), xiii. [Return to Section]

²  Many thanks to the Philosophical Life of Plants network and its 2022 gathering in Bristol, where I first encountered Arber’s work. [Return to Section]

³ Duane Isely, One Hundred and One Botanists (Iowa State University Press, 1994), 333. See also W.R. Matthews’s review of the book, “Intellectual Mysticism” in Nature 182 (1958), 681–682. [Return to Section]

⁴ Isis Brook, “Heroes of Botany: Voices of Dissent from the Western Tradition’s Devaluation of Plants” in The Vegetal Turn: History, Concepts, Applications, ed. Marcello Di Paola (Springer Nature Switzerland, 2024). Arber was the first female botanist to be elected as a Fellow of the Royal Society and the first woman to receive the Gold Medal of the Linnean Society. [Return to Section]

⁵ Kathryn Packer and Maura C. Flannery offer powerful insight into Arber’s history and earlier thought. See Kathryn Packer, “A Laboratory of One’s Own: The Life and Work of Agnes Arber, F.R.S (1879–1960), Notes and Records of the Royal Society of London 51.1 (1997), 87–105; and Maura C. Flannery, “Agnes Arber: form in the mind and the eye” International Studies in the Philosophy of Science 17.3 (2003), 281–300. [Return to Section]

⁶ Flannery, “Agnes Arber,” 282. Thomas is much more dismissive than Flannery lets on here, relegating Arber’s later life to that of a quiet contemplative existence irrelevant to scientific concerns. [Return to Section]

⁷ Packer, 92. [Return to Section]

⁸ Packer’s account of this time is helpfully detailed: “To summarize, the Balfour Laboratory’s history explains why Agnes Arber, a distinguished member of the botanical community, came to be working in her own home during a period in which science became professionalized and women gained access to many scientific institutions. It has been stressed by several people, including her daughter, and implied by Agnes Arber herself, that she enjoyed the quiet and intense atmosphere of working alone at home. However, the archive material has shown that, whatever the problems or benefits of this move in the long run, it was not a choice Arber made herself, it was a position forced onto her in a matter of two or three weeks” (see page 96). [Return to Section]

⁹ Many philosophers reflect on the question of the “One and the Many,” but William James’s The Pluralistic Universe is a profound modern set of lectures on the question (James, A Pluralistic Universe, University of California Libraries[Longmans, Green, and co., 1909]). Like Arber, James resists attempts to simply reduce the question to the Absolute or the “One” for a more multiplicitous view of reality. [Return to Section]

¹⁰ Arber, Manifold, xi. [Return to Section]

¹¹ Arber, Manifold, 28. [Return to Section]

¹² Agnes Arber, The Natural Philosophy of Plant Form (Cambridge University Press, 1950),  210. We might observe a Western coloniality in her approach to Classics here. More on that at the end of this essay. [Return to Section]

¹³ Arber, again: “The scientist deals with impersonal problems and his results are ‘public,’ and adapted for being expounded verbally (or by technical symbols) in their completeness; the contemplative, on the other hand, finds in the Unio mystica a fusion of his own individuality with the Absolute, the significance of which outdistances any conceivable expression in words” (Manifold, 19). [Return to Section]

¹⁴ Arber, Manifold, 17. [Return to Section]

¹⁵ Agnes Arber, The Mind and the Eye (Cambridge University Press, 1954), 120. Arber consistently used the patriarchal writing convention “he/him” to refer to third persons in general, as was the practice in those days. [Return to Section]

¹⁶ Brook, “Heroes,” 56. [Return to Section]

¹⁷ “We may sum up these considerations by saying that, to arrive at the fullest understanding of any individual plant form, we have, first, to realise it accurately by means of sensuous perception; secondly, to get the completest possible picture of it with the mind’s eye—a picture which receives sculptural solidity from the data gathered by touch, the internal concreteness from knowledge of anatomical structure; and, thirdly, to advance beyond this representation, so as to grasp its underlying and surrounding context of significance, and to see it in its living aspect, and in its relation to other forms” (Arber, The Natural Philosophy, 4). [Return to Section]

¹⁸ Stella Sandford, “Seeing Plants Anew,” Aeon, https://aeon.co/essays/what-plant-philosophy-says-about-plant-agency-and-intelligence. [Return to Section]

²⁰ Michael A. Sells, Mystical Languages of Unsaying (The University of Chicago Press, 1994), 2. [Return to Section]

²¹ Michael Marder: “Plants are the weeds of metaphysics: devalued, unwanted in its carefully cultivated garden, yet growing in-between the classical categories of the thing, the animal, and the human (for the place of the weed, much like that of existence itself, is precisely in-between) and quietly gaining the upper hand over that which is cherished, tamed, and ‘useful’ ” (Plant-Thinking: A Philosophy of Vegetal Life [Columbia University Press, 2013], 90). [Return to Section]

²² Brook, 58. [Return to Section]

²³ Arber, Manifold, 7. [Return to Section]

²⁴ Ibid., xi. [Return to Section]

²⁵ Arber, Mind, 46. [Return to Section]

²⁶ See, for example, Donald F. Duclow’s treatment of Nicholas of Cusa in Masters of Learned Ignorance: Eriugena, Eckhart, Cusanus (Ashgate, 2006). [Return to Section]

²⁷ See Catherine Keller, Cloud of the Impossible: Negative Theology and Planetary Entanglement (Columbia University Press, 2015). [Return to Section]

²⁸ Arber, Manifold, 70. [Return to Section]

²⁹ Ibid. [Return to Section]

³⁰ Ibid., 71. [Return to Section]

³¹ Banu Subramaniam, Botany of Empire: Plant Worlds and the Scientific Legacies of Colonialism, (University of Washington Press, 2024). Also see Chris Boesel and S. Wesley Ariarajah, “Introduction: The Whence and Whither of ‘Divine Multiplicity’” in Divine Multiplicity: Trinities, Diversities, and the Nature of Relation, eds. Chris Boesel and S. Wesley Ariarajah (Fordham University Press, 2014). [Return to Section]

³² This extends to her theory of the leaf as a “partial shoot” (see Brook, “Heroes”) as well as to a constant querying of the edges of reductionist approaches to Darwinian evolution, including the positioning of science as a discourse located in time. You can see evidence of this as early as Chapter 10 of Arber’s Monocotyledons (1925). See also Vittoria Feola, “Agnes Arber, historian of botany and Darwinian sceptic,” British Journal for the History of Science 52.3 (September 2019): 515–523. Importantly, as Maura Flannery writes, “This is where we get to a major reason why Arber is not better known today: she is often labeled as being anti-evolution, when in fact, what she questioned was not the fact that species change over time, but the idea that natural selection is the dominant mechanism for that change” (“Agnes Arber in the 21^st Century” The Systematist 24 [2005], 15). [Return to Section]

³³ Arber, Manifold, 105. In this passage Arber  again mentions Nicholas of Cusa’s complicatio as “folding together” and explicatio as unfolding. [Return to Section]

³⁴ Reflecting on the strategies of panentheism, see Catherine Keller, “The Body of Panentheism” in Panentheism Across the World’s Traditions, eds. Lorilai Biernacki and Philip Clayton (Oxford University Press, 2014). [Return to Section]

³⁵ Arber, Manifold, 118. [Return to Section]

³⁶ Michael Marder, Plant-Thinking: A Philosophy of Vegetal Life (Columbia University Press, 2013), 11. [Return to Section]

³⁷ Sells, Mystical Languages, 12. [Return to Section]

Erickson, Jacob. "The Vegetal and the Manifold: Agnes Arber’s Botanical Panentheism" in Thinking with Plants and Fungi: Interdisciplinary Explorations of Ecology, Mind, and the More-than-Human World, edited by Rachael Petersen, Russell Powell, and Natalia Scott Schwein. Center for the Study of World Religions, Harvard Divinity School, 2026.  https://doi.org/10.70423/0003.01