Caesar’s Last Breath

by | Jun 21, 2019


Caesar’s last words in 44 B.C.E. were “Et tu, Brute?”* His last breath, shortly thereafter, consisted of 25 sextillion air molecules. Each of us breathes, with every breath, at least one molecule of those 25 sextillion air particles that were a part of Caesar’s last breath. (25 sextillion is 25 followed by 21 zeros and looks like this: 25,000,000,000,000,000,000,000)

The air we breathe consists primarily of nitrogen (78%), oxygen (21%), a smattering of water vapor, and traces of argon, carbon dioxide and other gasses.  Yes, surprisingly, CO2 only makes up 0.033% of air.  When you exhale, your exhaled breath is about 4% CO2.

Anything released into the atmosphere spreads quickly because air is constantly on the move.  Photons from the sun warms air at the equator more than air north or south and causes changes in temperature and pressure.  This creates winds and the expansion and contraction of the lower and higher atmosphere.  During the day the lower atmosphere expands and then at night it settles back down as it cools. Thus, air is being tousled, churned and mixed all the time.

A breath seems like such a small thing compared to the Earth’s atmosphere, but remarkably, if you do the math, you’ll find that roughly one molecule of Caesar’s air will appear in your next breath. And it doesn’t stop there. In the same way, you might currently be inhaling Cleopatra’s perfume, German mustard gas and even particles exhaled by dinosaurs.” – Sam Kean, author of the book “Caesar’s Last Breath” in BBC Science Focus

At the smallest level, air molecules continuously jostle against one another at hundreds of miles per hour and ricochet like pool balls.  In a matter of weeks, the molecules in any given volume of air will circumnavigate the globe.  After a few years the original molecules will be evenly distributed throughout the lower atmosphere.  Air’s eternal cycling quality does not apply to many pollutants and organic compounds as they are often heavier (and so hang around) and/or are typically broken down by chemical reactions before they can complete their around the world trip.

So, when Caesar breathed his last breath he sent approximately 25^21 molecules of air mixture into the atmosphere.  Some of the CO2 probably got trapped and digested by plants in a nearby garden but the vast majority of his exhaled molecules began to fan out over an ever-widening area.  Within a decade, that breath had disbursed completely around the earth and most of it is still in circulation.  Thus, you breath some of everyone’s prior breaths with each inhale you take. We’re all connected!

*”Et tu, Brute” is Latin and translates in English to “Mmmmm, it smells like you are wearing Brut today.”


  1. The vastness of creation presented with such majestic intimacy surely must be the calling card of a loving God.

    • Kevin – I guess it depends on perspective. Here’s story to that point:
      There are these two guys sitting together in a bar in the remote Alaskan wilderness. One of the guys is religious, the other is an atheist, and the two are arguing about the existence of God with that special intensity that comes after about the fourth beer. And the atheist says: “Look, it’s not like I don’t have actual reasons for not believing in God. It’s not like I haven’t ever experimented with the whole God and prayer thing. Just last month I got caught way
      from the camp in that terrible blizzard, and I was totally lost and I couldn’t see a thing, and it was fifty below, and so I tried it: I fell to my knees in the snow and cried out ‘Oh, God, if there is a God, I’m lost in this blizzard, and I’m gonna die if you don’t help me.'” And now, in the bar, the religious guy looks at the atheist all puzzled. “Well then you must believe now,” he says, “After all, here you are, alive.” The atheist just rolls his eyes. “No, man, all that was was a couple Eskimos happened to come wandering by and showed me the way back to camp.”

  2. Oh Dang it! That must go for farts as well.

  3. Another winner. And it got me to laugh as well.


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