After the Greeks settled and created their own writing system, they also began dabbling in a very important aspect of humanity; philosophy. Before this time period, religion reigned supreme as the way in which to answer the unknown. Various gods allowed good or bad harvests, they controlled the weather, et cetera. Around when the Greek city-states were forming, new thinkers had risen up to try and explain the world through rational and natural explanations instead of religious ones. One of these thinkers was Thales of Miletus.
Thales of Miletus lived from around 624 to 546 BCE and was born in Miletus (off the coast of Turkey). Now because of how long ago Thales of Miletus lived, there is not a lot of physical writings by him that we still have today. However, we know about him through the references of other great philosophers such as Diogenes and Aristotle. Thales of Miletus (I know, long name) was also interested in politics and was a successful businessman. Thales of Miletus observed that weather conditions made better olive harvests, as opposed to the common belief that good harvests were a result of praying to the gods.
Due to his observation and a prediction of a year of good weather, Thales of Miletus bought out all of the local olive presses and then rented them out to people when they inevitably needed them. This made him super rich. Also, he was apparently very good at geometry and astronomy. One year he predicted a total eclipse of the Sun in 585 BCE. Achieving this solidified Thales of Miletus' view that the world had natural causes, and reason and observation would be able to reveal the inner workings of the universe.
So what was the first thing that Thales of Miletus asked as one of the first philosophers? He wondered what the universe was made out of. He believed that everything could be reduced into one singular substance which could account for the entirety of everything. This belief is called Monism (mono meaning one). Monism would take different shapes throughout history, but the first substance thought to be the substance of the cosmos was water.
Thales of Miletus believed that if there was a single substance of the universe, it would have to be something which everything could be formed, something essential to life, something capable of changing, and something capable of motion. These basic principles seemed to be the obvious components of everything, and water fits all of the criteria. So Thales of Miletus assumed that everything, no matter how it appeared, was made of water somehow.
Now, no one really thinks everything is made of water today. That philosophical thought is long gone. But that is not why Thales of Miletus is important. He is important because he was one of the first philosophers to use rationality and observation in order to explain the world, as opposed to using faith. This is philosophy's starting point, and so he will forever be influential in that regard.
