Keep the Gap: The Most Important Lesson I Took From The Richest Man in Babylon

I try to read The Richest Man in Babylon by George Clason at least once every 2-3 years. I just finished it again last week, this time by audio book. That was the first time I listened to it and it was a completely different experience. I seemed to pick up more of the lessons this time. Not sure why, but I’m glad I did.

If you’ve never read it, it was first published in 1926, and teaches timeless principles of personal finance through a collection of parables set in ancient Babylon. At the center of the book is Arkad, a once-poor scribe who becomes the richest man in Babylon by learning a handful of simple rules about earning, saving, investing, and protecting money.

As friends, merchants, laborers, and others seek his advice, Arkad shares the lessons that transformed his financial life - most famously the “Seven Cures for a Lean Purse.” Beneath the ancient setting and talk of gold coins, the message is remarkably modern: wealth has less to do with how much money passes through your hands than with what you consistently do with it.

The 7 Cures referenced in the book are:

1. Start thy purse to fattening.
   Pay yourself first. Save at least 10% of everything you earn before spending on anything else.

2. Control thy expenditures.
   Live below your means. Distinguish genuine necessities from desires that expand to consume whatever income you have. Create a budget that protects your 10% savings.

3. Make thy gold multiply.
   Invest your savings. Money sitting idle isn't enough—the money you've accumulated should itself begin producing additional money. This is essentially the principle of compound growth.

4. Guard thy treasures from loss.
   Protect your principal. Don't chase returns you don't understand. Seek advice from people who actually have expertise in the thing you're investing in, and prioritize getting your money back over getting rich quickly.

5. Make of thy dwelling a profitable investment.
   Own your home when doing so makes financial sense. Clason argues that directing housing expenditures toward ownership can build wealth and eventually reduce the cost of living.

6. Insure a future income.
   Prepare financially for retirement/old age and for your family. Build assets today that can provide income when you can no longer - or no longer want to - work. In modern terms: retirement accounts, investments, pensions/Social Security, income-producing assets, insurance, etc.

7. Increase thy ability to earn.
   Invest in yourself. Develop your skills, knowledge, judgment, and professional abilities so that your earning power continually increases.

In plain language, Arkad advises you to save money, spend less than you earn, invest the difference, make sure you don’t lose money while doing that, buy a house, invest for the long run, and work on growing your income.

Pretty simple, right? Simple, but not always easy. But I can tell you from experience that it is sound advice and it works. The problem with it is that it’s not sexy. It’s boring. It takes a long time. You get impatient with it. But, it works.

One of the areas where most people screw up, me included, is in principle #7: Increase thy ability to earn. It’s not that they fail to increase their ability to earn. Most people’s income does actually increase over time as they gain additional skills and experience at their job/career. The problem comes with the lifestyle creep that comes along with that increase in income.

As our income rises, so too do our expenses.

Let’s look at a couple of examples.

A person earning $60,000 who gets to $120,000 has created an enormous wealth-building opportunity. But if the $60,000 lifestyle becomes a $110,000 lifestyle, very little has actually changed. The house gets bigger. The car gets nicer. Vacations become more expensive. Restaurants get better. Subscriptions multiply. And somehow the person making twice as much money still feels like they need their next raise.

This segues into what I have started to call “Keep the Gap.”

The gap between what you earn and what it costs to live your life is the engine of wealth.

And increasing income creates an opportunity to dramatically widen that gap.

The math makes the point even more stark:

Imagine someone earns $75,000 and spends $67,500. They're following Clason's advice and keeping 10%:

Income: $75,000
Lifestyle: $67,500
Wealth-building: $7,500 (10% of $75,000)

Now suppose over the next several years they develop their skills and increase their income to $150,000.

There are two possible paths.

Path A — Lifestyle follows income

Income: $150,000
Lifestyle: $135,000
Wealth-building: $15,000

They're still saving 10%. Technically they're doing everything right.

But compare that with:

Path B — Keep the Gap

Income: $150,000
Lifestyle: $80,000
Wealth-building: $70,000

The first person doubled their income and doubled their annual investment.

The second person doubled their income and increased their annual investment more than ninefold.

That's the opportunity most people miss.

Clason's 10% rule is brilliant when you're getting started because it establishes the habit of paying yourself first. But I think there's a more powerful rule once your income starts growing:

Don't save the same percentage of every raise. Save most of the raise.

So if you go from $75k to $85k, perhaps you let yourself enjoy $2k–$3k of that improvement and automatically direct the remaining $7k–$8k toward investments.

Do that repeatedly throughout a career and something truly remarkable happens: your income and your lifestyle gradually decouple.

To summarize, here are five practical behaviors for preventing lifestyle creep:

1. Establish your definition of “enough.” Decide what a genuinely good life costs before your income becomes much larger. Otherwise your definition of enough will endlessly move with your income. Trust me, that goalpost ALWAYS moves.

2. Save raises, not just income. Keep Clason's 10% as the floor, not the target. Commit in advance to investing perhaps 70–80% of future increases in income. Keep the Gap.

3. Be careful with recurring upgrades. A $5,000 vacation is a one-time expense. A house that costs $2,000 more every month permanently raises the amount of income required to sustain your life. Lifestyle creep becomes dangerous when luxuries turn into fixed overhead.

4. Upgrade intentionally. The point isn't deprivation. Some upgrades genuinely improve life. Spend more on the things you deeply value and resist automatically upgrading everything else simply because you can afford it.

5. Measure the gap. Instead of obsessing over income alone, track income minus lifestyle. Someone earning $300,000 and consuming $280,000 may be building wealth more slowly than someone earning $150,000 and living happily on $75,000.

And there's an even deeper angle here that I think we vastly underestimate:

Lifestyle creep doesn't just cost money. It costs freedom.

Every permanent lifestyle upgrade raises your personal break-even point.

A bigger mortgage means you need more income. Expensive car payments mean you need more income. Private clubs, boats, second homes, expensive habits and recurring luxuries all create another little obligation your future self has to satisfy.

Eventually you can become wealthier on paper but more dependent on your income than you were before.

That's the paradox that traps us into the very slavery we were trying to avoid by making more money in the first place.

The purpose of increasing your earning ability shouldn't merely be to afford a more expensive life.

It should be to make your existing life increasingly easy to afford.

Eventually your assets can produce substantially more than your lifestyle consumes. And at that point money begins buying something far more valuable than nicer things:

It buys optionality.

You can work because you want to rather than because your lifestyle requires it.