When in 1880 Francis Galton asked his friends how clearly they could visually imagine a breakfast-table, he was shocked to find several of them unable to do so at all.

To my astonishment, I found that the great majority of the men of science to whom I first applied, protested that mental imagery was unknown to them, and they looked on me as fanciful and fantastic in supposing that the words 'mental imagery' really expressed what I believed everybody supposed them to mean. They had no more notion of its true nature than a colour-blind man who has not discerned his defect has of the nature of colour. They had a mental deficiency of which they were unaware, and naturally enough supposed that those who were normally endowed, were romancing.1

To Galton, a "visual image is the most perfect form of mental representation,"2 and he never imagined someone could lack the ability entirely. Galton's less visually imaginative friends, however, were equally surprised in reverse. They believed the 'image' in 'imagine' to be a mere metaphor; that nobody could actually visualize a breakfast-table.

Galton, an early proponent of scientific psychology (and, incidentally, eugenics), decided to study the phenomena. He asked everyone from scientists to painters to schoolchildren about the vividness of their mental imagery, and found (among other things) that children tended to imagine particularly vivid images. Describing what would eventually be called synesthesia, Galton ends his study with mention of a man who associated numbers with images and colors. His conclusion is that representations of the most basic concepts, like numbers, are innately visual. As people get older and learn more complex representations, like language, their need to rely on visual cues decreases. Sometimes, they lose the mental imagery skill entirely.3

Commenting on Galton's study of mental imagery, Alexander Bain, another prominent figure in early scientific psychology, wrote with some consternation:

At the lower end of the Charter-house gradation, the power of visualizing is given as 'nil'. One can hardly be expected to rest content with an answer like this. The scene of a cricket match, or of a ball, ought to be recalled to the minds of those benighted boys, whose imagery is darkness visible, and the nature of their recollection of such scenes minutely probed. What ideas do they possess of anything? Do they find any available substitutes for the visualising power? How do they get through life at all?
-Alexander Bain, Mind 1880

Bain's question "How do they get through life at all?", alongside Galton's conclusion that visual thought is innate, exemplify the fundamental link many place between thought and sight. Consider here the root of 'imagination', a word used to describe any mental flight, visual or otherwise. The link was so central to some ancient Greek and medieval European philosophers that they believed the visual representation of a thought to be the essence of the thought itself. A century and a half after Galton's study on mental imagery, people are still shocked to discover such variability in internal visualization. The inability to form mental images was only recently given a name, 'aphantasia',4 and the renewed psychological interest has been the spark behind many recent public self-discoveries.5

This connection between imagery and thought, so deeply-seated that people continue to be surprised when discovering the two are not so neurologically tightly-bound, is a fitting starting point. Much of this collection explores the three-way connection between visualization, ontology, and epistemology. Ontology is the study of how we sort and structure things, and for much of written history, people have employed tree and network visualizations to represent these ontological structures. Epistemology is the study of how we know things, and visual forms turn out to be so compelling that their usage influences what we know and how we teach it to others. The way images subtly mediate the bridge between epistemology and ontology is a theme I return to in several ensuing vignettes.

Visual mediation is part of a mutual reliance between epistemology and ontology, a co-evolution. The metaphors we employ to shape the world in turn shape our ability to know it, and what we know of the world influences what shape we give it. Medieval Christian theology inherited and imposed a strict hierarchical order between Heaven and Earth, often represented as a branching tree. The tree metaphor influenced philosophers and scientists for centuries, shaping what was worth studying and even influencing the philosophized relationship between God, reality, and humankind. Through a combination of global6 and feminist7 interventions, alongside shifting scientific tides, networks slowly replaced trees in visualizations, metaphors, and ontologies. They are now as embedded in society as trees once were, touching everything from architectural design to business organization to academic disciplines.

But I've gotten ahead of myself. Understanding the image/thought link requires some historical context.

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  6. Ranganathan, S.R. “Colon Classification and Its Approach to Documentation.” In Bibliographic Organization. Papers Presented before the Fifteenth Annual Conference of the Graduate Library School, 94–105, July 24-29, 1950.

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