Excerpt:

People have long asked:

"What is the world made of?" and "What holds it together?"

What is the World Made of?

Why do so many things in this world share the same characteristics?

People have come to realize that the matter of the world is made from a few fundamental building blocks of nature.

The word "fundamental" is key here. By fundamental building blocks we mean objects that are simple and structureless -- not made of anything smaller.

Even in ancient times, people sought to organize the world around them into fundamental elements, such as earth, air, fire, and water.