Ancient Greek Perception of the Ocean

To the ancient Greeks the ocean was an endless stream that flowed forever around the border of the world, ceaselessly turning upon itself like a wheel, the end of earth, the beginning of heaven. This ocean was boundless; it was infinite. If a person were to venture far out into it--were such a course thinkable--he would pass through gathering darkness and obscuring fog and would come at last to a dreadful and chaotic blending of sea and sky, a place where whirlpools and yawning abysses waited...