> For the complete documentation index, see [llms.txt](https://ethereum-model-of-the-world.gitbook.io/ethereum-a-model-of-the-world-1/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ethereum-model-of-the-world.gitbook.io/ethereum-a-model-of-the-world-1/part-i/one-simple-idea.md).

# One Simple Idea

> ### *“We Model the World, and the World Models Us.”*

#### -Karl Friston

This is a principal idea introduced in the [Free Energy Principle](https://en.wikipedia.org/wiki/Free_energy_principle) developed by neuroscientist Karl Friston, though it is rooted in philosophical origins as many concepts are. Initially designed to study the brain, the Free Energy Principle is a formal statement that explains how *any* ***self-organizing*** **living** or **non-living** system that is at ***equilibrium with its environment*** must **minimize its Free Energy**.

And that necessitates ***generating***** Models of the World**.

### What are Models of the World?

They are **Representations**, as the German philosopher Arthur Schopenhauer described in [*The World as Will and Representation*](https://en.wikipedia.org/wiki/The_World_as_Will_and_Representation). The world as we experience it,

> *“exists solely as ‘representation’ dependent on a cognizing subject, not as a world that can be considered to exist in itself – without the subjective experience within one’s mind.”* 

These concepts advance the works of thought leaders like [Immanuel Kant](https://en.wikipedia.org/wiki/Immanuel_Kant#Young_scholar), who was himself influenced by logicians and philosophers before his time.

![Have you ever questioned the nature of your reality?](/files/-MW0aDclyOwnjYabKiLL)

While these thinkers reasoned *logically* and *philosophically* that such a system of representations must exist for our **experience of the world**, the Free Energy Principle attempts to **objectify** such frameworks through ***math*** and ***statistics***.

Because this notion is so abstract, it is better elucidated through narrative, example, and analogy. For instance, 71% of the Earth’s surface is water. The most vital organs in our body also roughly have a 71% water composition:

![](/files/-MW0aDcmqaVjjoGRlpPK)

It can be tempting to chalk this up to chance, but a deeper connection is realized through the lens of the Free Energy Principle.

![](/files/-MW0aDcnP7xPaT7afJv5)

### So, what is Free Energy?

Put simply, it is the **maximum** **amount of energy** ***available*** for **work**. Within the Free Energy Principle framework, it is more specifically ***Variational***** Free Energy**. The definition can be prohibitively technical because it includes terms like the *Kullback-Leibler divergence, Laplace approximation, ensemble densities*, and related jargon to formally state what is illustrated here ([source](https://www.fil.ion.ucl.ac.uk/~karl/The%20free-energy%20principle%20-%20a%20rough%20guide%20to%20the%20brain.pdf)):

![](/files/-MW0aDcoUwnWOWgqTWya)

Fortunately, there is an ***intuitive*** and ***conceptual*** way to understand these technicalities. Before diving into the Free Energy Principle to understand how Ethereum is a Model of the World, we will review a concept so **fundamental** that it pervades the **Hierarchy of Sciences**:

![](/files/-MW0aDcppX4Jw7u3bGDD)

**First principles thinking** leads the way.