Originally posted by Lark
I think you're right, he did so because he was interested in the principle of refraction, like if you put a twig in water it may appear to be bent because of the angle at which the waters surface interacts with and distorts the image of the twig.
I'm more interested in why people ask these questions and what it matters, unfortunately Descartes was the start of a philosophical trend through Kant, up until Nietzsche which was positively individualistic in its turning away from all other things or persons and simply affirming the self as more real or important than anything else.
Even though Stirner thought he was being original with his philosophy of the ego and attack on other philosophers he was just part of a wider objective trend, I think that's more important than whether or not the theorising can be proven as objectively true.
Holistic thinking and harmonising can a very, very poor second in the legacy of these grand theories.