Buddhist cosmology is like a big story about how the world works according to the teachings of Buddhism. Theravada school is a group of Buddhists who follow the earliest teachings of Buddha. They believe in many different levels of existence, like different worlds or universes.
Imagine a big circle, that's called the "world system" in Buddhism. Inside the world system, there are many different worlds, like planets or galaxies. Some of these worlds have living beings like humans, while others have different kinds of beings like gods or demons.
At the center of the world system, there is a big mountain called Mount Meru. It's like the most important place in the whole world system. The gods and other beings all want to be close to Mount Meru because they believe it's a very special place where good things happen.
In Buddhism, there are six different realms of existence. These are like different states of being that a person can experience. The first three realms are called the "lower realms" and the last three are called the "higher realms." The lower realms are places where beings experience a lot of suffering and pain, while the higher realms are where beings have many good experiences.
The six realms are:
1. Hell realm: This is where beings go if they have really bad karma. It's a place of constant suffering and pain.
2. Hungry ghost realm: This is where beings go if they're really attached to material things like food or money. They're always hungry and can never get enough of what they want.
3. Animal realm: This is where beings go if they're ruled by their instincts and don't have much intelligence or self-awareness.
4. Human realm: This is where we live. It's a place where we can experience happiness but also suffering.
5. Deva realm: This is where the gods live. It's a very happy place where they have everything they need and want.
6. Brahma realm: This is the highest realm. It's a place of pure consciousness, where beings have no physical form and experience only pure bliss.
So in Buddhist cosmology, there are many different worlds and different levels of existence that beings can experience. The goal of Buddhists is to reach the highest level of existence, the Brahma realm, by following Buddha's teachings and living a good life.