Tales of Blood & Lemons

On the 12th December 1799, George Washington was outside, supervising his farm.

He’d retired as the first President of the United States of America just two years ago and was still an active 67 year-old.

It was a grimy winter’s day, shifting between snow, hail and rain as he rode around his plantation. 

He was a sticker for punctuality, so that afternoon to avoid running late for dinner he stayed in his wet riding clothes for a few more hours.

The next day he woke with a sore throat and a temperature, but he went outside again to oversee the work of his slaves.

That night he woke in severe pain struggling to breathe.

George Rawlins, an overseer at Mount Vernon, was called in to help.

He immediately extracted half-a-pint of blood from the former president. 

Bloodletting

Bloodletting was the most common medical practice performed by surgeons from antiquity until the late 19th century, a span of over 3,000 years.

People used to believe that everything was made from the four basic elements: earth, air, fire, and water. 

In humans these were seen as being four humors: blood, phlegm, black bile and yellow bile.

If someone was ill they believed that it was due to an imbalance of the four humors.

So to treat the symptoms you need to remove the excess of the humor that was causing the problem. 

Over the centuries the practice of bloodletting began to be used to treat almost all illnesses, far beyond the initial principles of humors.

With the limited abilities of medical science at the time, bloodletting was something practical and easy to administer.

It had the great benefit of giving people something active they could do to help.

Which is why the overseer, and George Washington who was a strong believer in the idea, decided to draw blood.

The 14th December

The next morning Washington’s close friend and personal physician Dr Craik arrived to help.

He bled Washington a second time.

Then two more doctors arrived to help, Dr. Gustavus Brown and Dr. Elisha Cullen Dick.

Washington was bled a third time.

At noon Washington was given an enema before he was bled for the fourth and final time. 

Sometime between ten and eleven that night George Washington died in great agony.

Over four pints of his blood were removed on that final day.

40% of his blood.

It’s now thought that he was suffering from severe epiglottitis (a viral throat inflammation), and the extensive amount of bloodletting resulted in him dying of hypovolemic shock (lack of blood).

Empirical Observation & Scientific Verification

By 1799 the ideas behind bloodletting had been thoroughly discredited for centuries.

When bloodletting was invented 3,000 years ago it was the bleeding edge of medicine.

At that time people exclusively used empirical observation to understand how the word worked (“I saw a person get better when blood was removed”).

They used deductive reasoning, and would try to solve a problem by thinking logically about how a cause and effect could be connected. 

The problem is that if what you observed is not clear, or you don’t understand it at all (the four basic elements and four homors), no amount of logic will help reach the correct conclusion.

This all started to change in the 16th and 17th centuries when scientific reasoning was first developed.

Experiments by Andreas Vesalius on anatomy in 1543 and William Harvey on circulation in 1628 exposed significant errors in the empiric theories that bloodletting was based on.

Vesalius’ publication De Humani Corporis Fabrica (On the fabric of the human body) is recognised as the start of the scientific revolution.

Between that time and Issac Newton’s Philosophiae Naturals Principia in 1687 the principles of scientific thinking replaced the culture of empirical observation as the primary way to make sense of the world around us.  

Scientific verification is the rigorous process of using controlled, repeatable experiments, statistical analysis, and peer review to confirm if an observation is reliable, moving beyond personal experience to objective, universal understanding.

“There are in fact two things, science and opinion; the former begets knowledge, the latter ignorance.” - Hippocrates

The Curse of Scurvy 

Scurvy is a terrible disease. 

With a long-term lack of vitamin C in your diet, your body starts breaking down at a cellular level.

It results in all sorts of symptoms including fatigue, swelling, bleeding from your gums and skin, losing teeth and bones becoming brittle. 

Untreated it is deadly.

In his book about scurvy, Stephen Bown shares a survival story written by a surgeon on a 16th-century English voyage that reveals the horror of the disease:

“It rotted all my gums, which gave out a black and putrid blood. My thighs and lower legs were black and gangrenous, and I was forced to use my knife each day to cut into the flesh in order to release this black and foul blood. I also used my knife on my gums, which were livid and growing over my teeth. . . . When I had cut away this dead flesh and caused much black blood to flow, I rinsed my mouth and teeth with my urine, rubbing them very hard. . . . And the unfortunate thing was that I could not eat, desiring more to swallow than to chew. . . . Many of our people died of it every day, and we saw bodies thrown into the sea constantly, three or four at a time.”

During the Age of Exploration (1500 to 1800), scurvy is believed to have killed at least two million sailors.

Between 1497-1499, Vasco da Gama lost 115 of his crew of 170, mainly to scurvy on his voyage to India.

Between 1519-1522, Magellan lost 200 out of 230 on the first circumnavigation of the globe.

And between 1740-1744, Commodore George Anson’s fleet suffered the worst medical disaster at sea on his voyage around the world, losing 1,415 men out of 1,854. *

For centuries empirical thinking kept failing to find a cure, because the symptoms were so confusing.

The chaplain of only ship to complete the journey of the six in Anson’s fleet wrote: “This disease, so frequently attending long voyages, and so particularly destructive to us, is surely the most singular and unaccountable that affects the human body: its symptoms are inconstant and innumerable, and its progress and effects extremely irregular.”

• The symptoms varied between each sufferer.

• There were significant differences in how quickly and severely the symptoms affected different people. 

• It takes at least a month of poor diet before any symptoms occur.

• It frequently happened on long sea journeys.

• But people could quickly recover back on land, surrounded by an overwhelming array of things that could have resulted in that positive change. 

• People could also suffer from scurvy on land too, so was that a separate problem?

A Controlled Experiment

The horrific loss of life on Anson’s voyage inspired Dr. James Lind to see if he could discover a remedy for scurvy.

While serving as a surgeon on HMS Salisbury in the Channel fleet he conducted a scientific experiment.

He divided 12 men with symptoms of scurvy into pairs and gave each group one of the alternative remedies people had been trying:

• 25 drops of elixir of vitriol (sulphuric acid, alcohol, sugar, and spices), three times a day (this is what Anson’s fleet had taken)

• A quart of cider a day

• A half pint of sea-water a day

• A paste of garlic, mustard seed, horse-radish, balsam of Peru, and gum myrrh, three times a day

• Two spoonfuls of vinegar, three times a day

• Two oranges and one lemon a day

Within a few days, the men who had been given the citrus fruits were well enough to start helping the others.

In 1753 Dr. Lind announced his findings in his Treatise of the Scurvy: “the result of all my experiments was that oranges and lemons were the most effectual remedies for this distemper at sea.”

Finally science had discovered the answer to the curse of scurvy.

With scientific verification, and through the use of controlled testing you can reach an accurate conclusion even if you have no understanding of the problem, what’s causing it or even why your solution works. 

Vitamin C was only isolated and fully understood in 1928.

Except it's not that simple.

Scientific verification was still a new idea and even Lind made mistakes.  

To try and solve the problem of keeping lemons preserved for long journeys, he switched back to an empirical approach.

He boiled and bottled the juice which destroyed most of the vitamin C and made his version of the cure ineffective.

And he didn't run further tests to discover this. 

He’d also buried the lede, briefly mentioning the experiment half way through the 450 paged book, among a lot of empirical conjecture.

So in the continued confusion it took four more decades before these essential findings were implemented. 

The Royal Navy finally made lemon juice rations compulsory in 1795.

And then it took even longer for civilians to adopt the cure, only being enforced in the 1867 Merchant Shipping Amendment Act.

The lengths of time involved are mind boggling. 

• George Washington died two and half centuries after bloodletting was disproven.

• Lemons were finally fully adopted over a century after the cure was proven.

• And that Washington died due to a reliance on empirical observation, just four years after the Royal Navy mandated lemons as a result of scientific verification. 

Nobelitis

Why did it take so long to learn?

Empirical thinking comes naturally to us.

Scientific thinking is challenging.

Even when we know better we have a tendency to fall back on personal observations and attempts at logic.

It can affect the greatest scientists of them all - Noble prize winners - at such an uncanny rate that it’s called Nobel disease or Nobelitis.

For example:

James Watson was awarded the 1962 Nobel Prize in Physiology or Medicine for his part in the discovery of the structure of DNA. But he also thought that dark-skinned people have a higher sex drive (not scientifically proven) because of their higher levels of melanin (also not scientifically proven).  

Linus Pauling won the 1954 Nobel Prize in Chemistry for his work on chemical bonds and then the Nobel Peace Prize in 1962 for his activism. Then he started to consume massive doses of vitamin C (120x the recommended daily intake) and argued that it could treat schizophrenia cancer (all of which is not scientifically proven).

Kary Mullis who won the 1993 Nobel Prize in Chemistry for development of the polymerase chain reaction also decided that HIV didn’t cause AIDs (which is scientifically disproven) and that he’d once met a fluorescent, talking raccoon (which is just straight bonkers).

It’s a mistake that happens in all facets of life, including in business.

We have a tendency to mistake opinions for facts.

• Ideas that are based solely on empirical observation are opinions.

  
  

• Ideas that have ben verified by scientific testing are facts.

Make sure you recognise the difference and don't catch Nobelitis.

The Value of Scientific Thinking

Between 2016 and 2019 researchers wanted to test the benefits of using more scientific thinking in business. 

759 startups of differing sizes and stages, in Milan, Turin and London, operating in a variety of sectors, were offered free training in entrepreneurship.

Half of the participants were given standard business training, 

The other half were given the same training, with an additional module in scientific thinking. 

Then the activities and results of the businesses were tracked for 38 weeks. 

There were two key results:

1: The scientific thinking business pivoted early and decisively, whereas the control group were more likely to continue to pivot in a drawn out search for success. 

They searched efficiently.

“A more efficient search raises the probability of success of ideas in earlier stages because it combines two effects: a higher probability of success and the ability to identify successful ideas earlier.”

“Think like a scientist: When you start forming and opinion, resist the temptation to preach, prosecute, or politick. Treat your emerging view as a hunch or a hypothesis and test it with data. Like the entrepreneurs who learned to approach their business strategies as experiments, you’ll maintain the agility to pivot.” - Adam Grant, Think Again

2: The scientific thinking firms grew faster, earning an average of €7,000 more than the control firms. 

They used methodic doubt. 

By having a better sense of the plausibility of their ideas and how to measure them, they were better at avoiding the continued pursuit of ideas that aren't working.  

“By focusing our energies on validated learning, we can avoid much of the waste that plagues startups today. As in lean manufacturing, learning where and when to invest energy results in saving time and money.” - Eric Ries, The Lean Startup

Opinions & Facts

Challenge your ideas.

Strategic intuition is essential to success in business, but the accelerator is the ability to test and verify your ideas quickly and effectively. Is it just an opinion or a fact?

Is it bloodletting or lemons?

“I used to be a science teacher.

One thing it taught me is to have a healthy regard for the difference between a fact and an opinion.

In science, establishing something as a fact is a daunting process. First you need convincing experimental data. Then you need to establish the reliability of your data by performing the same experiment and getting the same result. Then other scientists will “peer review” your experiment by trying to replicate the result.

Science doesn’t just accept something as a fact because someone with a big award or a fancy title says so. Even after a hundred years, scientists are still testing Einstein’s ideas about gravity and the speed of light.

The world of advertising and marketing couldn't be more different. If enough loudmouths say the same thing enough times facts are born.

These facts are rarely, if ever, validated and are often repeated ad nauseam in conference rooms and trade conferences.

In advertising and marketing “fact” is usually just the elongated shadow of some blowhard’s opinion.

- Bob Hoffman, The Ad Contrarian

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* The statistics on the crew sizes and survival rate on the voyages of the age of exploration are a best estimate. Record keeping at the time was poor and every study I can source arrives at different numbers for both the initial crews and the final tally.

Greenstone, G., “The history of bloodletting”, BC Medical Journal (2010)

Horecny, Z., “The Death of George Washington”, The George Washington Presidential Library at Mount Vernon, (2025)

Bown, S., “Scurvy: How a Surgeon, a Mariner, and a Gentleman Solved the Greatest Medical Mystery of the Age of Sail”, The History Press (2021)

Lloyd, C. C. “Limes, Lemons, and Scurvy”, United States Naval Institute (1965)

Price, C., “The Age of Scurvy”, Science History Institute (2017)

Baron, J. B., “Sailors' scurvy before and after James Lind – a reassessment”, Nutrition Reviews (2009)

Camuffo, A., et al, “A Scientific Approach to Entrepreneurial Decision Making: Large-scale replication and extension”, Strategic Management Journal (2024)

Hoffman, B., “The Ad Contrarian: Getting Beyond the Fleeting Trends, False Goals, and Dreadful Jargon of Contemporary Advertising”, Hoffman/Lewis (2008)