After learning about Thales, who as a philosophical optimist believed that the arche of the world was water, I started thinking about the reasons behind why he thought the arche was water. Things that Immediately came to mind were the obvious such as, the human body is primarily made of water, and same with the earth. Maybe Thales believed that the arche was water because water is the only substance that can completely change its own state, it is also the only substance that can take the shape of anything it is poured into. Water also flows, by Thales saying that the arche is water he may be saying that the world flows, and therefore the world is water. I'm sure there are many other reasons behind what made Thales think the arche was water, but these are the only things that came to mind when I thought about it.