Philosopher democritus believes that "the indistinguishable particles of matter-atoms and void are the origin of the world", which belongs to ancient naive materialism.

Atoms and void are the theories about the origin of everything put forward by ancient Greek atomic materialists leucippus and democritus. Marx expounded the profound significance of this thought in his doctoral thesis, believing that it acknowledged the existence of contingency in the system of atomic materialism.

Ancient naive materialism said:

Ancient naive materialism is the original form of three stages of materialism. According to Engels, naive materialism has the following basic characteristics: trying to find the unity of natural phenomena with infinite diversity in some concrete and tangible objects or some special things.

Naive materialism affirmed the material origin and unity of the world. Due to the limitation of knowledge level, a certain or specific material form is always regarded as the material basis of the origin of the world's material.