i read about descartes simply because his name popped in my head, and i needed to know where i knew him from. it seems he's the founder of modern philosophy and the one who first said "cogito ergo sum"(i think therefore i am). i held onto that statement thinking that that is as far as we can define our reality with absolute certainty. but after reading a little bit about descartes, i have since learned that his philosophy further elaborated to say that we know we exist in some capacity because we think, but we also know that an outside world exists separate from our own thoughts because in the very least, there is sensory information that is not self-generated.