Explained all things that come to be in nature spring from a finite number of principles: fire, air, water and earth. Anaxagoras posited an infinite number of principles.
Aristotle will say in Physics, that it is necessary that there be either one principle of nature or many. Each opinion has claimed the position of the philosophers. Some held that there was one principle, others many.
There were some who held there to be four principles of nature. Some even more, for even Empedocles posited the existence of friendship and strife, along with the four elements of fire, air, water and earth.
Empedocles held that the world has been made and corrupted many times. These are the cycles of Empedocles caused by generation and corruption on account of friendship and strife. For example, when the world is corrupted by friendship, gathering all into one, the world may then be generated again by strife and division. The distinctions in things would then follow from their being confused.
He also denied that these elements comes to be from each other.