Thoth (in Egypt) or Hermes Trismegistus (in Greece) was a great spiritual leader and teacher.  Part of his teachings are several basic principles.  The first principle says that "The All is Mind and Mind is the ALL".  Many find this idea hard to understand and even harder to accept, but it fits right in with Gnostic teachings and with the new science of Quantum Physics.  So what does it mean?
    Basically, everything that exists is thought and thought (or Mind or Consciousness) is the only thing that really exists.  The physicist  would say that matter is really just energy vibrating at certain frequencies.  In Gnosticism or mysticism, we prefer to say that all is Consciousness or all is Light (vibration).  
    Most people understand that everything that is man made existed first as thought in the brain of it's inventor, but have a hard time understanding that the final product is just thought too, but on a different level.   In Hermetism, they teach that the universe, including spiritual as well as material dimensions are all just thought in the Mind of God but, on the lower material levels, can be changed to some extent by the minds of humans.  In Gnosticism, we would agree with most of that except we say that the spiritual dimensions were created by the true God, ie, are thoughts in His mind, while the lower material dimensions were created by the demiurge or the fallen angels and is thought in their minds.  
    Some get the wrong idea from this and think that if everything is just thought, than it's not real and they don't have to obey the lays of physics.  That is not true for most of us.  We are also created by Consciousness, our spirit and soul by God, our physical body by the demiurge.  So, we are part of the great illusion and must obey it's laws.  We have to breath, eat, sleep, etc.  The only way to get out of that is by rising above that level of existence or Consciousness, to a higher, more spiritual level where different laws apply (there is law at all levels, sorry anarchists).  In Gnosticism, we believe that we need to not only raise ourselves to higher levels, but our entire world must be returned to it's original spiritual state if it is to survive.