Empedocles proposed that all matter is composed of four elements: earth, air, fire, and water. He believed that these elements could combine in different proportions to form different substances.

Thales of Miletus is often regarded as the first philosopher to develop a systematic theory of the universe. He proposed that water was the fundamental substance from which all things originated.

Democritus proposed that the universe is composed of an infinite number of indivisible particles called atoms. He believed that these atoms were in constant motion and could combine in different ways to form different substances.

Aristotle developed the theory of the four causes as a way of explaining the nature of reality. He argued that every object has four causes: material (the matter from which it is made), formal (the shape or structure of the object), efficient (the agent that produces the object), and final (the purpose or goal of the object).

Heraclitus believed that the universe is governed by a single, rational principle called the Logos. He argued that the Logos is responsible for the order and harmony of the universe.

Pythagoras is known for his theory of the transmigration of souls, which states that the soul passes through a cycle of birth, death, and rebirth. He believed that the soul is immortal and that it can be purified through a process of moral and intellectual development.

Empedocles argued that the universe is composed of two opposing principles, love and strife. He believed that these principles are responsible for the creation and destruction of all things.

Democritus is known for his theory of the void, which states that there is an empty space between atoms. He believed that this void is necessary for the atoms to move and interact with each other.

Leucippus believed that the universe is composed of an infinite number of worlds, each of which is governed by its own laws. He argued that these worlds are constantly being created and destroyed.

Empedocles is known for his theory of the elements, which states that all matter is composed of a combination of four basic elements: earth, air, fire, and water. He believed that these elements could combine in different proportions to form different substances.

Leucippus argued that the universe is composed of an infinite number of indivisible particles called monads. He believed that these monads were in constant motion and could combine in different ways to form different substances.

Democritus is known for his theory of the atom, which states that all matter is composed of tiny, indivisible particles. He believed that these atoms were in constant motion and could combine in different ways to form different substances.

Democritus believed that the universe is composed of an infinite number of worlds, each of which is governed by its own laws. He argued that these worlds are constantly being created and destroyed.

Aristotle developed the theory of the four causes as a way of explaining the nature of reality. He argued that every object has four causes: material (the matter from which it is made), formal (the shape or structure of the object), efficient (the agent that produces the object), and final (the purpose or goal of the object).

Democritus believed that the universe is composed of an infinite number of worlds, each of which is governed by its own laws. He argued that these worlds are constantly being created and destroyed.