Ocean Tides (ca. 1610–ca. 1687): Many of the great ancient civilizations originated near one of the oceans or broad seas of our planet. There can be little doubt that the close proximity of these expansive bodies of water had an impact on the development of scientific thought in these cultures. Of the greatest concern to early coastal societies, with regard to the ocean, would have been the ability to predict the occurrence of the daily tides. Navigation, and the subsequent trade routes that the waterways provided, were important to the success of a civilization. The study of tides for early scientists would have been a complex matter, as the timing and magnitude of the tides vary with each coastal location. Early philosophers, most likely those involved with the study of astrology, would have noticed that the position of the moon held some connection with the level of the tides. Since our moon was considered to be a perfect manifestation of the creator, tides were often viewed as the interaction of the gods with the physical Earth (see THE MOON).
While many early cultures developed theories on the origin of tides, the ancient Chinese were among the first to provide written records of their ideas. To the early Chinese civilizations, the tides represented a battle between opposing forces of nature. This was described as early as 300 B.C.E. in I Ching (Book of Changes) as a battle between the opposing natural forces called yin and yang. By the 2nd century B.C.E., the Chinese had related the tides to the phases of the moon, and by the 4th century they had developed an understanding that the moon was a factor in the occurrence of tides. While around the same period of time the ancient Greeks had also related the phases of the moon to ocean tides, the direct relationship between the two would not be fully