Fear, doubt, insecurity, illness, loneliness, death... These are difficulties in every human life, from which one cannot escape in any way, and for which no worldview, science, nor social life seems to be able to give comfort anymore. For the Westerner, thinking is a main problem. As a result of the development of science, there is a continually growing body of factual knowledge; but faith is left behind, as well as certainty in knowing, in science. If we look for consolation in times of doubt and loneliness, must we leave the realm of thinking and turn to different areas of our soul-life (such as to be more in-touch with our feelings)? Or is it possible in this time of rational thinking, that thinking is precisely the key to coming to a faith that is based on certainty in knowing? In this book we are summoned to learn to experience this problem of the Westerner (the problem of thinking) ourselves, in order to come from this gained experience to our own insight in the path which leads us away from the darkness of rational intellect. Just there, where twilight falls, we find the light that enlightens doubt and loneliness, but also illness and death. Knowing for certain is not modern, and one could say that this book is a revival of an outdated idealism. That objection can only be made if one overlooks the fact that a decisive step is made in this work, enabling all old questions to arise in a new light. It is the step of the self-experiencing of thinking, through which a self-knowledge becomes possible which adopts a scientific character on the one hand, and is at the same time the pathway to a modern mysticism. Thus sounds the ancient summons to the new self-conscious man in the 21th century -- GNOTHI SEAUTON, Man, know yourself!