Very good question. As far as I’m concerned, there is only an endless series of moments, but, because it’s rather clumsy to go into definition of what is a moment, I like to say that there’s essentially one eternal now. And in each of these “nows” we seem to be constantly recreated. Thus, as you say, without memory I have no clue whether I popped into existence right now in this very moment. Yet, when you manage to be aware of the moment when you are first “recreated”, when you catch the transition from what you insist to be a state of “unconsciousness”, you will know what I’m talking about. Seriously, if psychedelic “boosters” are not your thing, try meditation. It’s a harder path but the results are more solid and also easier reproducible. I, personally, prefer combination of both ^_^ Now, I wonder if it’s really the reason why I hysterically laugh at Descartes :D