Book excerpt: Existence: what it is and what we think it is engages logic and rational to expose and explain the defects of human opinions and beliefs that came into existence from human imagination rather than any precise, irrefutable knowledge, including that of knowing exactly what makes humans human, and knowing why everything that physically surrounds them - on Earth and beyond - always behaves within the states of physical reality and never any unreality.Yet, despite the seemingly overall human acceptance that physical existence (on Earth and beyond) constitutes physical reality, even the slightest examination of human notions and beliefs - including those accepted by science - shows just how much these notions and beliefs endorse and uphold physical unreality. The reason for such widespread acceptance of unreality amongst humans is due to their preference to believe the lies of those who advocate, for their own selfish reasons, that everything is possible, and that the security of all humanity can be assured by means of belief in intangible entities of gods, multi-dimensions, and time.It may appear improbable that the intentions of Existence: what it is and what we think it is to dismantle any of the erroneous notions and self-deceptions has much chance of success, considering how ingrained these beliefs are in human self-awareness. Still, it is possible that the disclosures and explanations provided in the book may lead some readers to realize that the future of mankind depends not on the usual attitudes of selfish wants and desires but on unrestricted understanding of physical reality - with all its limitations - which can teach humanity to carefully manage not just its future existence but that of all other inhabitants on Earth in its care.