Thomas Edison famously said that genius requires “1% inspiration and 99% perspiration.” Edison’s third criterion for would-be innovators is less well-known but perhaps even more vital: “a logical mind that sees analogies.”
Edison, father of the light bulb, recorded sound and moving pictures, was right. Many of the most important breakthroughs in history—including the printing press, the theory of evolution, the airplane, the assembly line and the computer desktop—were developed through the use of key conceptual analogies.
That’s because analogy is much more than a linguistic device; it’s a fundamental way of thinking. To make an analogy is to make a comparison that suggests parallels between two distinct things, explicitly or implicitly. And those who are most nimble at seeing parallels and connections, rather than just obvious differences, compete best.
Here are four rules for innovating through analogy.
Question conventional analogies
Always kick the tires on the analogies you encounter or consider. Some analogies ring true at first but fall apart on closer examination. For example, centuries of would-be aviators modeled their machines after birds in an attempt to flap their way aloft. But flapping had nothing to do with the intrinsic aerodynamics of flight; rather, it reflected challenges of propulsion unique to birds.
The Wright Brothers, by contrast, saw an analogy to the machine that they already designed, manufactured and repaired for a living—the bicycle. Both were unstable vehicles requiring nuanced balance and control in three dimensions; both fell if they lost too much forward momentum. The design decisions this analogy inspired enabled them to make history at Kitty Hawk.
Explore multiple analogies
No matter how seductive an analogy may be, be sure to examine several others before deciding which one might be most useful. Usually, more than one analogy can shed light on a given situation.
Charles Darwin, for example, developed his theory of evolution based on two fundamental analogies. The first analogy drew a parallel between geology and biology. Darwin reasoned that if a modest, meandering stream could erode grains of sand one by one to carve a mighty canyon, perhaps small, random changes in a plant or animal could influence its relative survival and reproductive rates over generations, gradually altering both form and function to yield new species.
Darwin’s second insight was to draw an analogy between breeding in agriculture and “natural selection” in the wild. Melding both analogies, he offered a revolutionary theory that not only explained biological evolution but also equipped people with a systematic approach for understanding gradual change in virtually any complex system.
Look to diverse sources
The art of analogy flows from creative re-categorization and the information that we extract from surprising sources. Take the invention of the moving assembly line. Credit for this breakthrough typically goes to Henry Ford, but it was actually the brainchild of a young Ford mechanic named Bill Klann. After watching butchers at a meatpacking plant disassemble carcasses moving past them along an overhead trolley, Klann thought that auto workers could assemble cars through a similar process by adding pieces to a chassis moving along rails.
Overcoming significant management skepticism, Klann and his cohorts built a moving assembly line. Within four months, Ford’s line had cut the time it took to build a Model T from 12 hours per vehicle to just 90 minutes. In short order, the moving assembly line revolutionized manufacturing and unlocked trillions of dollars in economic potential. And while in retrospect this innovation may seem like a simple, obvious step forward, it wasn’t; the underlying analogy between moving disassembly and moving assembly had eluded everyone until Klann grasped its potential.
Similarly, Steve Jobs recognized that the digital “desktop,” first developed but unappreciated at Xerox PARC, was an analogy with the potential to make computers accessible to millions of people—an insight he put to work when he launched the first Mac. That breakthrough machine (and the imitators that followed) quickly democratized computing and ushered in today’s information age.
Jobs always pushed for simplicity in design because, as he used to say, “Simplicity is the ultimate sophistication.” That’s how analogies work, too: They make complicated things easier for people to grasp by stripping them to their essence. The very best analogies make things as simple as possible—but no simpler.
— Mr. Pollack ’s latest book is “Shortcut: How Analogies Reveal Connections, Spark Innovation, and Sell Our Greatest Ideas,” from which this essay is adapted. He is a former speechwriter for President Bill Clinton.