How to Make Your Own Analogies
Create an analogy by choosing the relationship you want to explain, mapping it to something familiar, and testing whether the comparison helps your audience. Feynman’s light-wave example illustrates the process.
THE IDEA
How to Make Your Own Analogies
Analogies can help you explain something to another person or work through it yourself. To create one deliberately, start with the relationship you want to explain.
Step 1: Figure out the property or characteristic you are most trying to convey about a particular domain
Let’s say you are Feynman and want to explain to a group of laypeople how the human eye experiences and processes light waves. He starts with a specific property: you can learn about waves by observing what happens at a particular point.
Step 2: Find something concrete and ordinary to map this characteristic onto
You are probably already so used to thinking of sound or light waves as water waves—because scientists have been pointing to this analogy for centuries. So you draw on this association and say that light waves behave similarly to waves in a pool of water. Now, how do you communicate the above characteristic? Feynman once said that you could imagine a little fly floating on the water. The fly would bob up and down as the waves passed over it. This bobbing up and down would be its experience of the wave, but if it was a smart fly, it could gather all this data and begin to make a theory about what the waves were and where they were coming from, even if, being so small, it couldn’t gain a bigger picture.
Feynman used this to explain what happens when light waves enter the eye: the eyes detect the stimulus (analogous to bobbing up and down) and the brain pieces the data together to create a mental map of where they are coming from. In this way the brain constructs an internal model of the visible world around it. It’s the same as the fly coming to understand the waves that are moving it up and down.
Step 3: Adjust or discard your analogy if it isn’t working!
Your analogy’s success will depend on the quality of the relationship between the two things you are comparing. If you are trying to describe light waves hitting the eye using an analogy of an octopus in a supermarket buying cantaloupes, your listeners will exhaust all their brainpower just trying to guess how the two things fit together. An analogy highlights selected similarities. Here, the relevant comparison is between an observer detecting water waves and an eye receiving light. The imaginary fly need not resemble an eye in other ways. If your listener or student is hung up on the idea of a fly, then forget the fly and choose something else!
For each comparison below, ask which relationship it explains and where it stops being useful.
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The atom is like a tiny solar system (naturally, this analogy is useless if the person hearing it doesn’t know what a solar system is . . .).
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The spread of an infectious disease is like the spread of a wildfire. Only a small spark is needed, but if enough “fuel” is encountered, the spread could be exponential.
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Receiving a fecal transplant is a little like sowing wildflower seeds into bare soil.
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A probiotic supplement is compared to a bucket of water poured into the ocean. This conveys a proposed difference in scale; it does not establish what effect the supplement has.
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A science lesson is like an enzyme: an explanation can speed up a learner’s understanding, as a catalyst speeds up a reaction without being consumed by it.
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Metabolism is like an engine.
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Determining redshift by spectroscopy is a bit like recognizing a fingerprint on a stretched balloon: a pattern can remain recognizable even though its spacing has changed.
When to use it
Explaining a scientific principle to a non-expert audience (e.g., Feynman explaining light waves to laypeople).
Teaching a new skill by relating it to a familiar activity (e.g., comparing cooking to chemistry).
Self-learning: creating analogies to deepen your own understanding of a difficult topic.
Improving communication in business presentations by using concrete analogies to clarify abstract concepts.
FROM THEORY TO EVERYDAY LIFE
In practice
Feynman's Light-Wave and Water-Wave Analogy
To explain how the human eye processes light waves, Feynman likened light waves to water waves with a fly floating on the water. The fly bobs up and down as waves pass, representing the eye's detection of light stimuli; the brain pieces data together like the fly inferring the wave's motion.
Atom as a Solar System
An atom is compared to a tiny solar system to convey a central nucleus surrounded by electrons. It is a limited comparison: electrons do not follow the planets’ classical orbits, and the image only helps a listener who knows what a solar system is.
Infectious Disease Spread as Wildfire
The spread of an infectious disease is like a wildfire: only a small spark is needed, but with enough fuel, the spread can become exponential.
Fecal Transplant as Sowing Wildflower Seeds
Receiving a fecal transplant is likened to sowing wildflower seeds into bare soil—introducing beneficial elements to a depleted environment.
Probiotic Supplement as Bucket of Water into Ocean
Comparing a probiotic supplement to a bucket of water poured into the ocean suggests that the addition is small relative to the system. The size comparison alone does not show whether the supplement has an effect.
Science Lesson as an Enzyme
A science lesson is compared to an enzyme because a useful explanation can speed up understanding, just as an enzyme speeds up a chemical reaction. The comparison concerns the role of a catalyst, not every property of a teacher.
Metabolism as an Engine
Metabolism is compared to an engine, emphasizing the conversion of fuel into energy to power processes.
Redshift and Spectroscopy as Fingerprint on Stretched Balloon
Determining redshift by spectroscopy is like identifying a fingerprint on a balloon that has been stretched—the pattern changes in a recognizable way.
A MOMENT TO REFLECT
Put it to work.
Think of a complex concept you recently learned. Can you create an analogy that highlights its most important property?
Identify an analogy you frequently use. Is it mapping the correct single characteristic, or does it introduce irrelevant details?
When teaching someone, how can you test whether your analogy is working? What would you do if it isn't?
CONTINUE THE CONVERSATION
Source texts
- Richard Feynmans Mental Models by Peter Hollins