How the humble tree became our most powerful visual metaphor for organizing information and distilling our understanding of the world.
Why is it that when we behold the oldest living trees in the world, primeval awe runs down our spine? We are entwined with trees in an elemental embrace, both biological and symbolic, depending on them for the very air we breathe as well as for our deepest metaphors, millennia in the making. They permeate our mythology and our understanding of evolution. They enchant our greatest poets and rivet our greatest scientists. Even our language reflects that relationship — it’s an idea that has taken “root” in nearly every “branch” of knowledge.
How and why this came to be is what designer and information visualization scholar Manuel Lima explores in The Book of Trees: Visualizing Branches of Knowledge (public library) — a magnificent 800-year history of the tree diagram, from Descartes to data visualization, medieval manuscripts to modern information design, and the follow-up to Lima’s excellent Visual Complexity: Mapping Patterns of Information.
Lima writes in the introduction:
In a time when more than half of the world’s population live in cities, surrounded on a daily basis by asphalt, cement, iron, and glass, it’s hard to conceive of a time when trees were of immense and tangible significance to our existence. But for thousands and thousands of years, trees have provided us with not only shelter, protection, and food, but also seemingly limitless resources for medicine, fire, energy, weaponry, tool building, and construction. It’s only normal that human beings, observing their intricate branching schemas and the seasonal withering and revival of their foliage, would see trees as powerful images of growth, decay, and resurrection. In fact, trees have had such an immense significance to humans that there’s hardly any culture that hasn’t invested them with lofty symbolism and, in many cases, with celestial and religious power. The veneration of trees, known as dendrolatry, is tied to ideas of fertility, immortality, and rebirth and often is expressed by the axis mundi (world axis), world tree, or arbor vitae(tree of life). These motifs, common in mythology and folklore from around the globe, have held cultural and religious significance for social groups throughout history — and indeed still do.[...]The omnipresence of these symbols reveals an inherently human connection and fascination with trees that traverse time and space and go well beyond religious devotion. This fascination has seized philosophers, scientists, and artists, who were drawn equally by the tree’s inscrutabilities and its raw, forthright, and resilient beauty. Trees have a remarkably evocative and expressive quality that makes them conducive to all types of depiction. They are easily drawn by children and beginning painters, but they also have been the main subjects of renowned artists throughout the ages.
Among the legions of artists captivated by trees was the great Leonardo da Vinci. Shortly before his death, in one of his voluminous notebooks, Da Vinci worked out a mathematical formula for the relationship between the size of a tree’s trunk and that of its branches — he found that as a tree grows, the total cross-sectional area of all new branches is roughly equal to the area of the mother trunk or branch, no matter the height of the tree. Centuries later, scientific tests using computer-generated models of trees have not only found Leonardo’s formula to hold up across nearly every tree species, but also to explain trees’ remarkable resilience to wind and other external forces.
Indeed, Leonardo’s formula touched on the very thing that makes the tree such a powerful metaphor for organizing knowledge — its natural function not merely as a static object, but also as a system of relational dynamics. Lima writes:
Our primordial, symbolic relationship with the tree can elucidate why its branched schema has provided not only an important iconographic motif for art and religion, but also an important metaphor for knowledge-classification systems. Throughout human history the tree structure has been used to explain almost every facet of life: from consanguinity ties to cardinal virtues, systems of laws to domains of science, biological association to database systems. It has been such a successful model for graphically displaying relationships because it pragmatically expresses the materialization of multiplicity (represented by its succession of boughs, branches, twigs, and leaves) out of unity (its central foundational trunk, which is in turn connected to a common root, source, or origin.)
I was delighted to see a longtime favorite among the selections — Stefanie Posavec’s brilliant Writing Without Words project, a hand-drawn visualization of the “literary organism” in Jack Kerouac’s novel On the Road, depicting the sentences, words, and rhythm structures in the book.
The Book of Trees is a treasure trove of visual literacy, symbolic history, and cultural insight. Complement it with this visual history of tree diagrams explaining evolution and these glorious drawings of trees from Indian mythology, then revisit Rachel Sussman’s gorgeous photographs of Earth’s oldest living trees.
Images courtesy of Princeton Architectural Press