But if we are talking about ontology, about what really exists, then these philosophers would argue that we have to recognize that these words don't really keep the same precise referrent from moment to moment. What "I" or "you" refer to (in this ultimate sense) is constantly changing and always in the process of becoming something different. What "I" refers to right now isn't the same thing that it referred to a moment ago or that it will refer to a moment from now. There isn't any thing, any stuff, any substance or essence of one's self, that's persisting through time from moment to moment to moment. There's just the chain of causation, what the Buddhist call 'dependent origination'.