Last weekend, as I was pensively staring into nothingness on the DC metro, a stranger approached me and said, "A penny for your thoughts?" We struck up a conversation, then, two stops later, went our separate ways. But the idiom — a penny for your thoughts — lingered. And I couldn't help but speculate: What if the idiom were economically redeemable not just for musings spoken aloud, but the thousands of rapid-fire internal thoughts that go through my mind each day? If I got a penny for every thought I had, how rich would I be? Let's find out.

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A brief history of the idiom “A penny for your thoughts”

First used by English statesman Sir Thomas More in his 1522 book Four Last Things, the idiom "A penny for your thoughts" has retained the same meaning for nearly 500 years. In his text, he uses the saying to refer to a pensive vagrant on a pilgrimage: "As it often happeth that the very face sheweth the mind walking a pilgrimage, in such wise that, not without some note and reproach of such vagrant mind, other folk suddenly say to them, 'A penny for your thought.'"

But it wasn't really until 1547 that the saying gained any popularity in usage. Twenty-five years after More's book, a playwright named John Heywood put together a collection of proverbs he'd heard over the years (The Proverbs and Epigrams of John Heywood). Buried in its pages, beside gems like "Rome was not built one day" and "all that is well ends well," was "a peny [sic] for your thought."

When these texts were written, a penny was actually a considerable sum in England. Adjusted for inflation, it would amount to about 1.6 pounds, or $2.50 USD, today. Unfortunately for us, today's idiom remains the same: It has not taken inflation into account. So, in our hypothetical situation, we still get one penny (in 2016 dollars) per thought.

Calculating thought income

As of 2016, we humans have only scratched the surface of the science of our thought process. It remains unknown exactly how many thoughts we have each day — or what even constitutes a "thought" for that matter. But there are some estimates out there, and the best one comes from the University of Southern California's Laboratory of Neuro Imaging. Researchers at the lab conducted some rudimentary experiments with student test subjects and electrophysiological monitoring, and found that the average person has about 48.6 thoughts per minute. (Again, these studies are not peer-reviewed, and only serve as a rough estimate.)

Let's call it an even 49 thoughts per minute. That's 2,916 thoughts per hour, 69,984 per day, and 25,544,160 per year. Now, let's assume that every time you have a thought, you get a penny. Obviously, the idiom requires one to share said thought aloud — but since we want to maximize our thought to money conversion, we'll count all thoughts (internal or external) here. We'll also assume your brain thinks at a constant rate of 49 thoughts per minute throughout the day and night. Our 69,984 thoughts per day would grant us a healthy $699.84 per diem — or an annual take-home of $255,500.

On the economic spectrum, a $255,500 yearly salary would place you in the top 4 percent of all earners in the United States — but you'd still be a far cry from the 1 percent. In 2015, it took a whopping $450,000 per year salary to crack into the 1 percent. So, even if you did get a penny for literally every single one of your 25.5 million yearly thoughts, you wouldn't even come close to the average top earner in our country. But if you thought at a constant rate of 49 thoughts per minute 24 hours per day, you'd be able to join the 1 percent over time. Let's assume you thought at a constant rate from birth to death. Not accounting for future inflation/deflation, here's how much money you'd stack up over time: