From the preface: "One who undertakes to represent certain results of scientific spiritual research of the kind recorded in this book, must above all things be prepared to find that this kind of investigation is at the present time almost universally regarded as impossible. For things are related in the following pages about which those who are today esteemed exact thinkers, assert that they will probably remain altogether indeterminable by human intelligence. One who knows and can respect the reasons which prompt many a serious person to assert this impossibility, would fain make the attempt again and again to show what misunderstandings are really at the bottom of the belief that it is not given to human knowledge to penetrate into the superphysical worlds. For two things present themselves for consideration. First, no human being will, on deeper reflection, be able in the long run to shut his eyes to the fact that his most important questions as to the meaning and significance of life must remain unanswered, if there be no access to higher worlds. Theoretically we may delude ourselves concerning this fact and so get away from it; the depths of our soul-life, however, will not tolerate such self-delusion. The person who will not listen to what comes from these depths of the soul will naturally reject any account of supersensible worlds. There are however people-and their number is not small-who find it impossible to remain deaf to the demands coming from the depths of the soul. They must always be knocking at the gates which, in the opinion of others, bar the way to what is 'incomprehensible.'"