This book - Scientology: The Fundamentals Of Thought is excellent beginning book on Scientology.                What is the source of human consciousness? Human consciousness is a component or quality of life. A life form with a low level of consciousness is only aware of its surroundings, maybe only what is matter. Maybe a tree or plant falls into this category. A higher level of life may have a conciousness whereby it is able to see life as living and distinct from matter. Maybe a dog or pet is here. A higher level could be the awareness of being alive ourselves. Most people reach this and realize they are alive. But perhaps not all people are aware they are truly alive, butrather go through life in a daze day by day until they die.  When life is aware of its own awareness then that might be a very high level of consciousness indeed. The source of consciousness of course is ourselves, unless you want to name a higher life force that created the universe - such as God.  Perhaps an awareness of this higher infinite level of life - God, could be classified as a higher level again. But I am just guessing. What level of consciousness life pocesses seems to depend perhaps on the volume of life and how imbued it is into the physical universe.