Whenever I speak on the topic of dreams, I mention a very unusual sort
of dream, the "lucid" dream (see Chapter 8) in which the dreamer
knows he is dreaming and feels fully conscious in the dream itself. After
discussing some of the philosophical and semantic difficulties in defining
states of consciousness, I always ask whether anyone has the slightest
doubt that he is awake, that is, in a "normal" state of consciousness at
that moment; I have never found anyone who had difficulty in making
this distinction.
In introducing a book of readings on altered states of consciousness,
I find myself in a similar position: there is a multitude of philosophical
and semantic problems in defining just what "normal" consciousness
and "altered" states of consciousness are, yet at this instant I have not
the slightest doubt that I am in my normal state of consciousness. Yet
there have been a number of occasions in my life when I have not had
the slightest difficulty in realizing that I was in an altered state of consciousness
(ASC). Thus I shall give only the simplest sort of definition
of what an ASC is here and let the articles in this book flesh it out: our
knowledge of ASCs is too incomplete at this time for a tight conceptualization.