Imagine that I have a machine that I could plug you into for the rest of your life. This machine would give you experiences of whatever kind you thought most valuable or enjoyable - writing a great novel, bringing about world peace, attending an early Rolling Stones' gig. You would not know you were on the machine, and there is no worry about its breaking down or whatever. Would you plug in? Would it be wise, from the point of your own well-being, to do so?