<P> Heraclitus was famous for his insistence on ever - present change as being the fundamental essence of the universe , as stated in the famous saying , `` No man ever steps in the same river twice '' ( see panta rhei , below ) . This position was complemented by his stark commitment to a unity of opposites in the world , stating that `` the path up and down are one and the same '' . Through these doctrines Heraclitus characterized all existing entities by pairs of contrary properties , whereby no entity may ever occupy a single state at a single time . This , along with his cryptic utterance that `` all entities come to be in accordance with this Logos '' ( literally , `` word '' , `` reason '' , or `` account '' ) has been the subject of numerous interpretations . </P>
<P> Heraclitus was famous for his insistence on ever - present change as being the fundamental essence of the universe , as stated in the famous saying , `` No man ever steps in the same river twice '' ( see panta rhei , below ) . This position was complemented by his stark commitment to a unity of opposites in the world , stating that `` the path up and down are one and the same '' . Through these doctrines Heraclitus characterized all existing entities by pairs of contrary properties , whereby no entity may ever occupy a single state at a single time . This , along with his cryptic utterance that `` all entities come to be in accordance with this Logos '' ( literally , `` word '' , `` reason '' , or `` account '' ) has been the subject of numerous interpretations . </P>
who said you can not step into the same river twice
who said you can not step into the same river twice
Heraclitus
Heraclitus