During the time of the Presocratic philosophers, theorizing on metaphysics was an exceptionally popular subject. The biggest dialectic talked about was the primary principal that was the one substance which "made up" everything on the planet. Possible elements came from anything like air to fire, or even numbers. Thales, considered by many to be the earliest philosopher, believed that this one element was water.
Although this theory might seem odd in the modern world, it may have some truth behind it. Though the reason Thales chose this element cannot be answered with sureness, Aristotle says that Thales "probably derived his opinion from observing that the nutriment of all things is moist, and that even actual heat is generated therefrom, and that animal life is sustained by water. and from the fact that the sees of all things possess a moist nature, and that water is a first principle of all things that are humid." This is most likely the case, but we cannot be certain.
Thales was convinced that this was the origin of all matter. For instance, we are able to classify most objects" state into three simple categories: liquid, gas, or solid. Out of the four main elements used in the Presocratic era (earth, air, fire, and water), water is the only one that can interchange between all three states. Water may change forms, yet its essence never alters.
The water content of all living organisms ranges from about 65% to about 95%. Humans are at the low end -- about 65%. For example, if you weigh 200 pounds, you are 130 pounds of water (about 16 gallons).
Who knew that such a simple substance could be so essential to the life of all living things? We must take a moment to reflect upon the dependency we have for this necessity. Just think about it: have you or could you ever imagine going a day without any water at all? With our showers in the morning, cooking dinner in the kitchen, and the basic glasses of water, the average human uses seventy gallons of water daily! It is quite obvious that human beings and almost all other life on this planet would not exist without water.