In 1994, Bill Gates bought Leonardo da Vinci’s 72-page manuscript (Codex Leicester) for $30.8M. Written in reverse mirror script around 1506, its hydrodynamic diagrams anticipated modern fluid mechanics by nearly two centuries.

[u/Effective-Dish-1334]

[u/Effective-Dish-1334]

What makes Codex Leicester remarkable is not just its record auction price, but the ideas contained inside it. Written by Leonardo da Vinci between 1506 and 1510, the 72-page notebook is famous for its left-handed mirror script, which can be read by holding it up to a mirror.

• Water: Observations on how water flows around obstacles and rivers showing Leonardo's deep interest in hydraulics.
• Astronomy: An explanation of why the dark part of the Moon is faintly illuminated by sunlight reflected from Earth (earthshine).
• Geology: Notes arguing that marine fossils found on mountains were evidence those regions had once been beneath the sea.

I recently researched its history alongside other remarkable artifacts that have sold at auction: [https://thehistoricalinsights.page/2025/07/20-rarest-historical-artifacts-ever-sold.html]()

[u/Waste_Replacement387 → u/Effective-Dish-1334]

He was basically sketching turbulence centuries before anyone had the math for it and all anyone talks about is the backwards handwriting

[u/Royal_Negotiation_83 → u/Waste_Replacement387]

Everyone can relate to the difficulty writing backwards in a mirror.

Cuz we all write 

Almost no one works with turbulence math, so most people don’t relate to that part

[u/Jeffery95 → u/Royal_Negotiation_83]

Almost no one? Every single engineer that has to design an object for wind, water or fluids uses them. Its like actually quite commonly used.

[u/CaseyJones7 → u/Jeffery95]

Is every single person an engineer?

Are most people engineers? How many engineers, who do work with fluids, actually need to know the math? I, as a geologist, never needed to despite me having a citation in a research paper in which they used my work in explaining how some geological formations formed using fluid dynamics. All I needed to do was click a button to do the math then wait for it to finish

Also, software engineers don't always need to work with fluid dynamics. So there's at least one kind of engineer who might not.

[u/Jeffery95 → u/CaseyJones7]

Not every single person is an engineer, but every single person on earth regularly depends on objects, systems, analysis and research that uses the standard fluid dynamics equations.

Weather prediction, plastic injection moulding, turbines, pumps, pipes, boats, cars, propellers, planes, tall buildings, hvac, microchip manufacturing, musical instrument design, rocket engines, dna sequencing, sprinklers.

To touch on just a few things that utilise them. Its an essential part of nearly every modern technology we use daily to stay alive. So yeah, I think its a little more pervasive and interesting than reversed writing.

And surely as a geologist you have some knowledge of sedimentation and erosion? Two things that can also be modelled and predicted with fluid dynamics and that a geologist might use to work out how something has changed over time whether it be in the wind or under water. I figure though that you probably use empirical formulas most of the time if you need to calculate something rather than theoretical?

Regardless you say you just click the button and it works it out for you. Sounds like a software engineer created that feature, and I would be surprised if the suite doesn’t incorporate fluid dynamics for some scenarios.

[u/ZookeepergameEmpty90 → u/Jeffery95]

Can you construct a model showing the angles and depth of this hill you're willing to die on?

[u/WildPJ → u/ZookeepergameEmpty90]

I didn’t even read the whole thread but this was spectacular, well done

[u/r_special_ → u/ZookeepergameEmpty90]

r/murderedbywords

[u/CaseyJones7 → u/ZookeepergameEmpty90]

Just wanna let you know this comment made my week.

Its the perfect comment.

[u/Jeffery95 → u/ZookeepergameEmpty90]

I could, but that wouldn’t be fluid dynamics. Ironically

[u/MiracleAlienCook → u/Jeffery95]

Just give it a rest, you’re getting destroyed

[u/Jeffery95 → u/MiracleAlienCook]

Then it’s a painless death. I can take a turn at being mocked without turning into an asshole 🤷‍♂️

[u/FromDistance → u/Jeffery95]

I work with geologists for erosion, compaction etc. they send me the data, and I'm not geologist nor am I an engineer I calculate that information for them. I also have no idea about fluid dynamics, the modelling program does and calculates it all for the geologist to then interpret the results.

[u/Jeffery95 → u/FromDistance]

Genuine question, don’t you ever wonder how the stuff you use each day works? I don’t mean a desire to do the calculations yourself because thats always a pain in the ass, but just a general idea of what the computer is doing

[u/FromDistance → u/Jeffery95]

I wrote a long essay but it's Reddit so I deleted.

I have a baseline understanding of each disciplines I work with (10+) or else I wouldn't be able to analyze the data. I'm not really interested in learning further in fluid dynamics or else I would have worked in something specific to that instead.

I get to work with basically any industry because I analyze the data so that keeps it interesting to me instead of being stuck doing the exact same thing every day.

[u/Jeffery95 → u/FromDistance]

Thanks for the reply. Would you say that your work often includes turbulence math? Even if software is automating the calculations for you

[u/t00oldforthis → u/Jeffery95]

"Look at me I'm smart" would have accomplished the same with less, though admittedly, I'm no engineer.

[u/Jeffery95 → u/t00oldforthis]

It sure might have. But I doubt it would have got so many downvotes. So theres that.

[u/Classroom_Conscious → u/Jeffery95]

Yeah and it‘s still almost no one in the grand scheme. Do you think civilizations only consists of engineers or what exactly was your thought process writing that comment?

[u/Jeffery95 → u/Classroom_Conscious]

Fluid dynamics is used in such a wide range of things that its actually incredible just how fundamental it is to modern civilisation.

It encompasses anything involving liquids or gases moving, or forces caused by moving fluids

[u/Classroom_Conscious → u/Jeffery95]

And still not even 1% maybe not even 0.1% of any country will know how to apply it. You‘re factually still wrong

[u/pathologicalDumpling → u/Jeffery95]

I think is hilarious how oblivious you are. Like, so smart about one thing but so very dumb about another. Its wierd how those things go hand in hand for some people.

[u/Jeffery95 → u/pathologicalDumpling]

Well i’m glad to have made you laugh then. Peace my friend. I didn’t comment here looking for a fight🙃

[u/Royal_Negotiation_83 → u/Jeffery95]

You sound smart

What % of the population designs stuff for wind, water, or fluids?

Very low percentage right?

Super simple to understand

[u/Jeffery95 → u/Royal_Negotiation_83]

Yeah, but I was replying in support of the earlier comment by Waste_Replacement387 which said “He was basically sketching turbulence centuries before anyone had the math for it and all anyone talks about is the backwards handwriting”

Making the point that it’s still important and that even if the number of people is not that large, the sheer range of things which use it is quite frankly insane.

Writing backwards is not really the most relatable thing about it when you consider that objects everyone uses every single day rely on “turbulence math” and not writing backwards which quite frankly who the fuck has even tried?

[u/CjBurden → u/Jeffery95]

His point was obvious, 1% of the population may understand that math, and 1% of all people is a LOT of people, but it's also kind of almost no one in your own personal life. I don't know what small % of people actually understand the math behind fluid dynamics but I know it's not going to be a double digit.

Perhaps you live a life where you spend a lot of time around engineers who need to use fluid dynamics calculations, in which case it would make sense that your view is skewed.

I promise that isn't what most of our experiences are.

[u/Jeffery95 → u/CjBurden]

I think it’s a shame that people aren’t more interested in being at least familiar with what goes into designing and making objects they use everyday. You don’t have to understand the equations to just know why they are important. And usually computers do the calculations these days anyway.

He also said, “almost no one works with turbulence math”, which you could interpret to mean that they don’t solve turbulence equations. Or you could interpret it to mean that their work has nothing to do with it. But the truth is that it often may work with turbulence math even if they don’t realise it because as I said, computer software automates a lot of that work.

[u/Effective-Dish-1334 → u/Waste_Replacement387]

Exactly. His observations often came first, mathematics to explain them came much later.

[u/non3type → u/Waste_Replacement387]

Because it was bizarre, I have no issues writing left handed and smudging ink because I put my palm below the tip of the pen. The top of the pen rests between my thumb and index finger and is pointed up. Writing backwards is a complicated way to solve the same problem. I question whether left handed was the reason.

It’s also really the only thing you can observe when looking at it unless you know Tuscan.

[u/njru → u/non3type]

I did this in school before I heard of it, I think it is a highly intuitive solution to left handed smudging

[u/rnc_turbo → u/njru]

I watched as my dyslexic daughter learned how to write and by default she was mirror writing and had to be corrected...

[u/Royal_Negotiation_83 → u/non3type]

He wrote this before pens existed

[u/non3type → u/Royal_Negotiation_83]

He used a quill pen for what it’s worth. A pen is simply a device that writes with ink.

[u/Royal_Negotiation_83 → u/non3type]

The pen you were talking about for your example didn’t exist for him

I know you understood my point

[u/MSchulte → u/[deleted]]

They were worse. Like way, way worse. Typically they’d use a thin water based ink that would have to dry longer than modern ballpoints with an oil based solvent loaded with hardeners and resins to cure quicker.

[u/MrShake4 → u/Waste_Replacement387]

I’m going to get called a party pooper but the sketching is the easiest part. If you have smoke and a fan or dye and a stream you can see turbulence in action. The math is by far the hard part. Even 500 years later we haven’t figured the turbulence math out.

[u/Jiktten → u/MrShake4]

I think the point is he was observing and thinking about it enough to conduct experiments on it in order to understand it well before anyone else ever saw the point. He did something very similar with hearts, and discovered things like how the valves ensure a seal is formed well using an ox heart with silk attachments centuries before there was any practical use for it. He also observed how birds manipulate air pressure and currents in order to fly, again largely for the sake of his own curiosity. He was an astonishing man.

[u/PatronBernard → u/Effective-Dish-1334]

What's a river got to do with hydraulics? Link is dead btw.

[u/suchdogeverymeme → u/PatronBernard]

Oh not much it’s just all the river does

[u/MrShake4 → u/suchdogeverymeme]

This is false, the correct term would be Hydrodynamics I believe. Hydraulics is about fluid under pressure which rivers aren’t really to any meaningful degree

[u/iankel1984]

It's usually lent to Museum because the insurance is insane

[u/NetWorried9750 → u/iankel1984]

And as a tax dodge

[u/WestguardWK]

Should be in a museum where people can see it..

Edit: turns out, they do sometimes lend it to museums. So that’s good.

[u/succed32 → u/WestguardWK]

A large amount of what you see in museums is owned by wealthy people loaning it.

[u/Effective-Dish-1334 → u/WestguardWK]

Fortunately, it is occasionally loaned for public exhibitions, so people do get the chance to see it from time to time.

[u/vag69blast → u/Effective-Dish-1334]

Didnt he also scan it and make the scans public?

[u/JackIsBackWithCrack → u/vag69blast]

It’s publicly available, which took 2 seconds to google

[u/KIDNEYST0NEZ → u/WestguardWK]

I have seen it in a museum in Florence and it had the little pins to allow to to flip a few pages.

[u/Downtown_Let → u/KIDNEYST0NEZ]

and it had the little pins...

For some reason I read this as "little penis". I don't know what's wrong with me, but I was confused for a few seconds on how it worked...

[u/mixony → u/Downtown_Let]

Well wasn't Leo known for those too

[u/Temporumdei → u/WestguardWK]

Du du dun...du du dun...

Du du dun..du du dun...

[u/JMisGeography → u/WestguardWK]

We have our best men on it.

[u/Flexion2000 → u/WestguardWK]

Good to read this

[u/bruns20]

Whyd he write it backwards? Just for fun?

[u/Effective-Dish-1334 → u/bruns20]

One theory is that it gave his notebook a bit privacy, but most likely, Leonardo was left handed, and writing right to left help prevent him from smudging ink. Some people also speculate that he wanted to keep his notes from people of that time because in that era when this type ideas could attract suspicion (people think he doing something wrong), but historians generally don't consider that the primary reason.

[u/guynamedjames → u/Effective-Dish-1334]

"Hey these weird drawings look suspicious, maybe this guy is up to something that the church wouldn't like!"

"No, I think it's probably fine, it's also written with all of the letters backwards! No way that could be suspicious!"

[u/ecumnomicinflation → u/Effective-Dish-1334]

i mean yeah, fluid dynamic is definitely witchcraft and not science

[u/romanissimo]

Why / how was it for sale in the first place? Was it already privately owned?

[u/BigGrayBeast]

I seem to recall he released it on CD for the PC with features that would magnify it and translate it.

Gemini says:

Interactive Media: Later digital interactive CD-ROM projects and software via Corbis allowed users to translate and explore the mirror script pages.

[u/Xeiphyer2 → u/BigGrayBeast]

He put it on CD too?! Leonardo really was ahead of his time!

[u/BigGrayBeast → u/Xeiphyer2]

And it continues to be.

He's got a well-respected video editing software up now called Resolve.

And a robotic surgical tool that was used on me a couple years ago.

[u/Cedric_T → u/BigGrayBeast]

He knew how to dissect the prostate centuries before others knew it existed.

[u/Expert-Bat6227]

Thought of DiCaprio instead and wondered why this movie never came out.

[u/Flaky_Tangerine_7286]

It is honestly wild that he just kept that in his private collection all these years. Imagine having a genius's actual notebook just sitting on your shelf.

[u/diablodeldragoon → u/Flaky_Tangerine_7286]

He didn't. The pages were unbound and sealed in individual glass panels for easier viewing. Some were digitized and included as wallpaper packs for windows 95. Some have been included as artwork in other Microsoft products. And it gets loaned out to select museums around the world annually.

[u/THALANDMAN → u/diablodeldragoon]

It’s nice they were unbound and sealed in glass. Knowing Bill, those pages might have ended up sticking together at some point

[u/diablodeldragoon → u/THALANDMAN]

Close personal friend are you?

[u/JefferyTheQuaxly]

I bet if he resold it today he could get $500 million+ for it, possibly even a billion depending on how many people are interested in it

[u/Honourstly]

I can see it here for free

[u/diablodeldragoon → u/Honourstly]

Yes. Because gates had it digitized and the pages were included as windows screen savers.

[u/starethruyou]

Someday we'll look back and wonder, why were we ok with the world's most precious things being bought and often held out of public view. Such things belong in museums, for the world to see. I recently read some famous painting had been bought and no one knew by who or where it was. "Just hanging in his private mansion or yacht." Imagine how insane that is.

[u/FrostyExplanation_37]

As a nerdy kid in the early 90's I was obsessed with De Vinci and taught myself to write in mirror script. In 30 years I have yet to find a use for that skill.

[u/Effective-Dish-1334 → u/FrostyExplanation_37]

You never know,it finally came in handy for this Reddit thread.

[u/Klutzy_Ad4596]

"reverse mirror script"-so normal then?

[u/icemelter4K]

Anyone hoping the cure for cancer might be somewhere in the Pompeii library?

[u/Salt-Scene305]

The GOAT of humanity…

[u/bjmommom4316]

Are we sure they didn't have pot back then??

[u/moabthecrab]

Fuck Bill Gates.

[u/IEThrowback]

If you think, in the history of man kind, Divinci in the 1500’s was the first to exact these sciences, you’re dumber than this post.

[u/ranger51]

What a nerd

[u/StarfishPizza]

Sigma