Socrates is considered a classical philosopher, not a Pre-Socratic philosopher.

Thales of Miletus is often regarded as the first philosopher in the Western tradition.

Pre-Socratic philosophers were primarily concerned with understanding the fundamental nature of reality and the universe.

Democritus is known for his atomic theory, which proposed that all matter is composed of indivisible particles called atoms.

Anaximander proposed that the apeiron, an infinite and undefined substance, is the origin and essence of all things.

Empedocles proposed that all matter is composed of four elements, which interact and combine to form different substances.

Pythagoras and his followers believed that the universe is governed by mathematical principles and that numbers hold the key to understanding the cosmos.

Heraclitus argued that everything in the universe is in a state of flux and that change is the only constant.

Empedocles proposed that love and strife are the two opposing forces that drive the universe and bring about change.

Anaximenes believed that air is the primary substance from which all other things are derived.

Anaximander proposed that the universe is infinite and contains an infinite number of worlds.

Parmenides argued that the universe is a single, unchanging, and indivisible entity.

Empedocles proposed that the four elements interact and combine to form different substances through the forces of love and strife.

Democritus proposed that atoms are the fundamental building blocks of matter and that their motion and interactions give rise to the properties of different substances.

Heraclitus believed that the universe is in a state of constant flux and that the conflict between light and darkness is the driving force behind change.