A sample of the 300+ images featured in The Book of Circles: Visualizing Spheres of Knowledge

The Book of Circles

Visualizing Spheres of Knowledge

After 4 long years of research, roughly 2,000 exchanged emails, 50,000+ written words, plenty of sketches and notes, The Book of Circles: Visualizing Spheres of Knowledge is finally available for pre-order on Amazon (officially out on May 2). You can follow updates on Twitter and Instagram.

How did it begin?

It was February 2011, and I had just finished giving a lecture at the Image in Science and Art Colloquium, organized by the University of Lisbon’s Center for Philosophy of Sciences. After I’d answered a few questions from the audience, one of the many professors in the auditorium stood up and asked, “Why do most of the visualization models you showed tend to follow a circular layout?” As the chair of the session, entitled The Emergence of Information Visualization, I was not only intrigued by her question but also somewhat vexed that this plainly evident observation had never occurred to me. “That’s a great question,” I said, pausing, and followed with a candid reply: “I don’t exactly know why.” To say this question lingered with me for quite some time would be an understatement.

Later that same year, in September 2011, while presenting my first book Visual Complexity: Mapping Patterns of Information at the New York Public Library and retelling this story in private to an audience member, I became enthralled by the mention of an experiment that established a correlation between circular shapes and happy faces. From that point on, I became consumed by this topic. It took me a few years to articulate my thoughts, but in many ways, The Book of Circles constitutes an answer to that original question.

Advance copy of The Book of Circles: Visualizing Spheres of Knowledge
A 2-page spread of the Frontispiece and the title page of The Book of Circles next to the Coelifer Atlas illustration (1559).

Why Circles?

Circles are truly everywhere. We can witness this elemental shape in faraway planets and stars; in earth formations such as mounds, craters, and small lakes; in the sections of tree trunks and plant stems; in the moving ripples on the surface of water; in a variety of leaves, fruits, shells, rocks, and pebbles; in the eyes of our fellow humans and other animals; as well as in cells, bacteria, and microscopic organisms.

Over time, the circularity exhibited in nature also became a chief guiding principle of human culture, emulated and reinvented in art, religion, language, technology, architecture, philosophy, and science. Used to represent a wide range of ideas and phenomena pertaining to almost every domain of knowledge, the circle became a universal metaphor embraced by virtually every civilization that has ever existed. We can see them as an organizing model in the cities and buildings we inhabit, the objects and tools we use, and the symbols and diagrams we construe to make sense of the world around us.

The interesting question is: why?

Of all possible models and configurations why is the circular layout such an exceptionally popular choice? This book aims to answer this question in three distinct ways: first, by providing a context for the universality of the circular shape as a cultural symbol in all domains of human knowledge, across space and time; second, by describing a set of perceptual biases, identified by cognitive science in recent years, that explain our innate preference for all things circular; third, by developing a comprehensive taxonomy of twenty-one visual archetypes for depicting information, which showcases the diversity and flexibility of the circular design.

With more than three hundred images, the book is a celebration of the enduring appeal of the circle, not just in the realm of information design, but in every sphere of human expression.

A sample of 200 images featured in the book


As some attentive readers might notice, The Book of Circles is similar to my previous title The Book of Trees, not just in its name, design, and layout, but also in its choice of a subject: a universal visual metaphor used for centuries across the globe. However there are some noticeable differences in its structure. Whereas The Book of Trees traces an evolutionary history of the tree diagram by showcasing all images and models in a chronological order, The Book of Circles intentionally mixes time and space to better convey the universality and timelessness of the circular layout. This is why you may notice a contemporary project from, say, 2012 adjacent to one from the fifteenth century. Moreover, The Book of Circles is broader in scope, which means that next to the multitude of examples from information visualization you will find many specimens from other disciplines, such as art, architecture, biology, cartography, archeology, and astronomy.

From the beginning it became clear that if the book’s taxonomy attempted at some level of inclusiveness, its reach would need to extend well beyond the domain of information visualization and look much further back than our present-time. Why should we contemplate history, one may ask? The answer is simple: because the past continuously revisits the present. Notwithstanding our advanced modern tools and piles of new data, we continue to use visual metaphors that are similar and at times identical to those used to convey knowledge throughout history. In addition, many of these enduring visual motifs are also highly adaptable and have recurrently traversed disparate disciplines. The juxtaposition of seemingly contrasting areas and time periods is one of the unique aspects of the book and, ultimately, a testament to the circle’s exceptional adaptability.

An evocative juxtaposition displayed as a 2-page spread in the book’s Introduction. Left: Dome of the Basilica of Superga, Turin, Italy, ca. 1717–31. Photograph by David Stephenson, from his book Visions of Heaven (PAPress, 2005). Right: Detail view of the Compact Muon Solenoid, Large Hadron Collider, Cessy, France, 2008.
A set of projects from the first of twenty-one visual archetypes featured in the book. The diversity is evident. Juxtaposed here are an art project created inside a petri dish, an illustration of the geocentric model, an image of Jupiter’s north pole, and a map of 10,000 porn stars. The projects span more than 500 years, from the 15th century to 2013.


The book opens with an extended Introduction that provides a rich history of humanity’s long-lasting fascination with all things circular. It starts by exposing the principle of circularity in our material culture, from primordial human settlements and modern cities, to numerous physical products and artifacts. It then delves into the predominance of the circular shape in the evolution of ideograms, alphabets, and symbols, before expanding on its most prevalent universal associations — perfection, unity, movement, and infinity. The Introduction ends with a set of evolutionary explanations for our proclivity to rounded shapes, based on several studies and experiments in the domains of cognitive science and human perception.

2-page spread from the book’s Introduction.
A set of circular logos and marks featured in the Introduction.
Illustration featured in the Introduction. Robert Fludd. Integræ Naturæ Speculum Artisque Imago (Mirror of the whole of nature and the image of art). ca. 1617. Courtesy of Beinecke Rare Book and Manuscript Library, Yale University.

A Taxonomy of Circles

Following the Introduction, A Taxonomy of Circles expands on the motivations for the classification underpinning the entire volume, as well as the rationale for each visual archetype and respective family. Coming up with the final taxonomy was arguably the hardest task of all — yes, harder even than managing permissions for 300+ images —, and the countless scribbled notebook pages (see below) attest to the arduousness of this undertaking.

The vast number of charts, diagrams, maps, blueprints, and photographs featured in the book were arranged in twenty-one unique patterns based on their visual configuration and then grouped into seven archetype families. Each family comprises three patterns. While the twenty-one individual models were left unnamed, in part to highlight the weight of its visual motif, the seven families have descriptive labels, respectively: (1) Rings & Spirals, (2) Wheels & Pies, (3) Grids & Graticules, (4) Ebbs & Flows, (5) Shapes & Boundaries, (6) Maps & Blueprints, (7) Nodes & Links.

Early sketches and notes: the beginning of the book’s taxonomy.
Numerous pages of drawings and annotations, some more meaningful than others.
The book’s Table of Contents exposing its final structure.
Pages from the section A Taxonomy of Circles which expands on the classification of the various visual archetypes featured in the book.


The Book of Circles (8.8 x 10.8 inches) is larger than The Book of Trees (8 x 10.5 inches) and almost the same size as Visual Complexity (9 x 11 inches). With 272 pages, The Book of Circles, like Visual Complexity, is denser than The Book of Trees (208 pages), and perhaps more significantly, it has the largest number of images of the three books, with roughly 310 charts, diagrams, maps, illustrations, and photographs.

Full cover spread of The Book of Circles: Visualizing Spheres of Knowledge.

If you made it this far, I can assure you there’s much more to see inside the volume. The Book of Circles: Visualizing Spheres of Knowledge is available for pre-order on Amazon (officially out on May 2). In the meantime, you can follow updates on Twitter and Instagram.

*Note: This post contains excerpts from the book.