For those interested, Mark Twain made an appearance on the
    season cliffhanger of STAR TREK: THE NEXT GENERATION.  His main
    dialogue concerned how the Universe may be filled with life and
    that Earth was probably not meant for the sole use of humanity,
    a fairly advanced notion for 1893.

        Does anyone have a listing and brief description of where
    Twain writes about such concepts?

        Regards,

        Larry Klaes