All is water

All matter is composed of water as its basic substance

The ancient Greek philosopher Thales posited the idea that "all is water" as one of the first abstract explanations for the origin of matter. Just as the abstract notion of a building encompasses every thing from homes to arenas and temples, the idea that all is water similarly offers an idea that unifies all matter in the world as a single substance.

In Thales's time it was commonly believed that matter was composed of four elements: air, earth, fire or water. Yet for Thales this theory was incomplete. Through his observations of the world, he concluded that everything has at least in part, some water in it. The oceans are obviously composed of water, but water is also found in animals, plant life, clouds and even in rocks, which do not appear to be wet, yet have a degree of moisture to them. For Thales this led to the conclusion that of the four elements., water must be the most important. If water is present everywhere , he reasoned, it must be the fundamental substance present in all things.

Even though the notion that there are only four elements and that water is the most important is no longer given  credence, the idea is renowned more for what it did not presume, rather than for it's accuracy. Prior to Thales and his aquatic thesis, the ancient Greeks approached questions of origins and explanations in terms of myths and gods. Thales's idea turned such thoughts away from the supernatural and instead toward an abstract nation that explains everything. In that idea lay the foundation for Greek philosophy, science and naturalism and all it bore.