another random thought

The quote "I think therefore I am," I think (ha!) is a bunch of crap, what about the existence of the rock sitting on the ledge of a cliff "It sits therefore it is?" The above quote maybe talking about the soul? I don't know. But I think it's a failed attempt at explaining existence/reality. While thought provoking, I believe it only goes as far as consciousness/self-awareness, but not as deep as to existence. Why are we here so to speak. another thought; how egomanical is it to "define" reality, what is reality? perception? collective understanding of what is? I don't believe there is a correct answer, if there is you are God.