"The central problem of philosophy, of religion, of all psychology is one so pervasive and so hard to come to grips with that it is largely ignored, just as fish ignore water. The solipsists deal with it and so did you in ULTIMATE EGOTIST (and so did I, quite differently, in THEY). It is the problem of the individual ego, the awareness of “I.” There you sit, inside your skull. How long have you been there? Always. How long will you be there? Always. Environment changes—even your body, even your penis and balls, are nothing but environment. The “I” remains, the one unchangeable thing…and a thing utterly unaccounted for in all philosophy, all religion. Of, the double-talk on the subject has endless, but but that is what is has been: double-talk. Until we know how consciousness hooks onto matter and why and where it comes from, we don’t know anything. And we don’t."
Robert A. Heinlein