Definitions, Metaphors, Similes, and Analogies

Take a tip from Einstein. In one of his famous papers published in 1905 when he was 25 years old, “On the Electrodynamics of Moving Bodies,” he completely transformed our understanding of physical laws and introduced his theory of relativity. In order to do this, he first proposed that the laws of physics are absolute, then he made both time and distance relative. Equations aside, to help us accept what was then an unthinkably brash concept, he wrote about how we merely understand time as a condition of simultaneity:

We have to take into account that all our judgments in which time plays a part are always judgments of simultaneous events. If, for instance, I say, “That train arrives here at 7 o’clock,” I mean something like this: “The pointing of the small hand of my watch to 7 and the arrival of the train are simultaneous events.”

Note what Einstein turns to as he aims to help us re-invent our notion of time: trains and clocks. In other words, he uses comparisons to things that we see as everyday. In particular when we contemplate science, we turn to comparisons—often by using similes, metaphors, or analogies—to simplify and to define. Such comparisons, when deployed well, can have the impact of the proverbial “light bulb” illumination for our readers—they understand suddenly, and hopefully they agree. And even if they disagree with our ideas—and Einstein’s paper on relativity was first rejected in its dissertation form, so take comfort—they have to consider them carefully.

Well-made comparisons, then, make us think, and the rhetorical tools by which we compare, such as metaphor, are handy, well-established, and universal. In fact, to explain what happened to him in 1905 with the explosion of his seminal papers and the birth of the world’s most famous equation, Einstein even used a metaphor: “A storm broke loose in my mind,” he famously said.

Providing Definitions

An important consideration in writing personal statements is when to provide definitions of key terms and concepts. The decision can be driven largely by audience and context, based on your audience’s likely level of understanding of the subject matter and the importance of the definition to the context of your essay.

At times, the material itself will be technical enough and important enough to context that you will need to supply a quick definition, as in this excerpt from a personal essay about neuroscience appearing in Chapter 4:

One of the projects I worked on during that summer was developing a diagnostic procedure for HIV encephalitis using PK11195, a ligand for the peripheral benzodiazepine receptor present on the mitochondria of macrophages.

Here, the definition of PK11195 is important to audience and context—both of which are clearly scientific—and the efficient wording demonstrates that the writer is both comfortable with the language of science and understands her project. In this same essay, however, the writer did not specifically define “HIV encephalitis,” “ligand,” and “pathogenesis,” fully aware that her audience members would already be familiar with these terms.

A further example from Chapter 4, written by a student studying medieval literature, is a more conversational and expansive definition:

Ogam is not a spoken language, rather, a code of inscriptions that gave the Irish language an alphabet and supplied the Irish people with a means of writing on stone, wood, and other natural elements with relative ease.

In this essay, the writer’s goal is to study Ogam in graduate school, so she supplies a contextual and historical explanation of its meaning in plain, direct language.

For help in supplying definitions, don’t hesitate to turn to authoritative sources, including your advisors and dictionaries specific to your field, citing your sources as needed.

Making Fundamental Comparisons

In addition to definition as a stylistic device, one of the best ways to make fundamental comparisons in writing is by using analogies, similes, and metaphors. Analogies, similes, and metaphors can be used to compare unlike but arguably similar things, either by implicit or explicit comparison. Such comparisons help aid our understanding and can be used to clarify or strengthen an argument, and they do so with efficiency. As with definitions, issues of audience and context help guide us in deciding when to employ these devices.

Here, we need not worry about exact distinctions among similes, metaphors, and analogies, other than a reminder that when we use them we often rely on phrasings such as “like” or “as,” and that when we make a fairly loose comparison we might use quotation marks around the words whose meaning we’re “stretching” (as I just did). Here are just a few commonly used similes, metaphors, and analogies from various disciplines:

In discussions of grammar, we might refer to a colon as acting like a flare in the road—a symbolic promise that something important is coming. A semicolon in a sentence’s middle acts like a caesura does in music or verse—as a timely pause linking two related parts.

In biology, mitochondria are often referred to metaphorically as the powerhouse of the cell, while the liver is loosely referred to as the body’s “garbage can.”

In discussing fungi, there’s a bright yellow fungus that grows on wet logs in the northwestern US, and it can be compared visually to a pat of melting butter. Underground, the roots of some mushrooms resemble the legs of a toe-standing ballet dancer.

In information technology discussions, we often speak of cyberspace as a metaphorically parallel world, with clipboards for saving information, surfing as virtual travel, and gophers allowing us to tunnel through to some desired goal.

As examples from personal essays written by students, what follows are a few fundamental comparisons that writers made through analogy, simile, and metaphor, with their surrounding material further explaining the comparisons. Notice how none of the comparisons are difficult to grasp, but all are illuminating.

These ripples of space-time curvature, called gravity waves, are radiated outward much like ripples in a pond.

The model uses the compartmentalized cascade to treat the intrinsic pathway as a “black box” leading to the output of thrombin in the common pathway.

I established a home for myself in a metaphysical and emotional space: the space where my family, passions, and goals all intersect.

As these writers did, when composing personal essays you should consider the similes, metaphors, and analogies available—even if they are commonly used—as efficient ways to demonstrate stylistic creativity, represent your understanding of a topic, describe related phenomena, and discuss fundamental concepts important to your field.