The Reason You Should Study 100 Year Old Books

There is a strange paradox in the world of business. We are obsessed with the new. We want the newest marketing hack. We want the latest software tool. We want the trend that started five minutes ago.

But if you look at the most successful thinkers, they spend very little time looking at what is new. They spend almost all their time looking at what is old.

They are using a mental model known as The Lindy Effect.

The Lindy Effect is a theory about the life expectancy of non perishable things, like ideas or technologies. It states that for every year an idea has survived, its remaining life expectancy doubles.

If a book has been in print for fifty years, you can expect it to be in print for another fifty. If a business principle has worked for one hundred years, it will likely work for one hundred more.

This is the opposite of human life. If a human is ninety years old, they do not have ninety more years to live. But ideas work backwards. The older they are, the stronger they are.

This concept changes how we should look at business advice. It splits information into two categories: Tactics and Principles.

Tactics vs Principles

Tactics are things that work right now. They are the hacks. The trends. The specific software updates.

Tactics expire quickly. If you learned how to maximize your reach on Facebook in 2014, that knowledge is useless today. The algorithm changed. The interface changed. The tactic died.

Principles are different. Principles are the deep structures of how the world works. They do not change because human nature does not change.

The Psychology of Persuasion

Consider sales. The technology of sales changes every decade. We went from door to door visits, to cold calls, to emails, and now to AI automation.

If you only study the technology, you are always restarting from zero.

But the psychology of why people buy never changes. The need for status remains the same. The fear of missing out remains the same. The desire for belonging remains the same.

A salesperson who understood human status in 1920 would still be dangerous today. The tools are different, but the human operating system is exactly the same.

History Rhymes

This is why reading business biographies is so profitable. It is easy to dismiss a biography of John D. Rockefeller because he lived in the 1890s. You might think his world has nothing to do with yours.

You would be wrong.

Rockefeller did not have the internet. But he understood monopoly power. He understood how to crush competition by controlling the supply chain. He understood pricing pressure.

When you read about how Rockefeller consolidated the oil industry, you are actually learning how modern tech giants consolidate the digital industry. The players change, but the game remains the same.

Renting vs Owning Knowledge

Think of learning like an investment.

When you learn a tactic, you are renting knowledge. It works for a year or two. Then the market shifts. The lease runs out. You are forced to go learn something new just to keep up.

When you learn a principle, you own that knowledge forever.

Foundational economics like supply and demand will still matter in fifty years. Mental models like Inversion or Second Order Thinking will help you make better decisions for the rest of your life.

Do not chase the noise. Find the signal. Look for the ideas that are Lindy.