Descartes saw that the self was the god principle (self-verifying truth) of consciousness. If one took away the self, the contents of consciousness would cease to exist. If one saw the self as illusion, the world would be viewed as illusion. Then consciousness would be empty of self-verifying truths.
Because the "I" exists not as a thing but as a process, the self is a conversion of a process (of consciousness) to a thing by giving form to the process through its relation to the contents of the process.
This attempt to convert a process into a thing generates a paradox. The process can only be identified as thing (the self) within the context of the contents of the process, but the thing thus described cannot encapsulate the process because it lies outside that context.
While one might be tempted to attribute causal and so ontological primacy to the contents, it does not account for what the process is in terms of consciousness itself.
