In 560 B.C. there was an Ephesian philosopher called Heraclitus whose basic idea was that everything is in a state of flux. Everything was changing from day to day and from moment to moment. His famous illustration was that it was impossible to step twice into the same river. You step into a river; you step out; you step in again; but you do not step into the same river, for the water has flowed on and it is a different river. To Heraclitus everything was like that, everything was in a constantly changing state of flux. But if that be so, why was life not complete chaos? How can there be any sense in a world where there was constant flux and change?

The answer of Heraclitus was: all this change and flux was not haphazard; it was controlled and ordered, following a continuous pattern all the time; and that which controlled the pattern was the Logos, the word, the reason of God. To Heraclitus, the Logos was the principle of order under which the universe continued to exist. Heraclitus went further. He held that not only was there a pattern in the physical world; there was also a pattern in the world of events. He held that nothing moved with aimless feet; in all life and in all the events of life there was a purpose, a plan and a design. And what was it that controlled events? Once again, the answer was Logos.

William Barclay: The Gospel of John, Volume 1