- Heraclitus (ca. 540 to 480 B.C.) : Heraclitus refers to the sixth century B.C. Greek philosopher who referred to the mind as an enormous space whose Boundaries could never be reached.

Heraclitus also suggested fire as the physis because in its presence nothing remains the same. He viewed the world as in a constant state of flux and thereby raised the question as to what could be known with certainty.

According to him, "becoming" is the state of everything in the universe. Nothing is static and unchanging; rather, everything in the universe is dynamic, that is, "becoming" something other than what it was.