The thoughts from which the presentation of the content of this book have grown and that form its basic support have been indicated in the Preface of the 1914 edition following this. To what was said then, I should like to add something connected with a question that lives more or less consciously in the soul of one who turns to a book on the riddles of philosophy. It is the question of the relation of philosophical contemplation to immediate life. Every philosophical thought that is not demanded by this life is condemned to remain barren even if it should attract for awhile a few readers of contemplative inclination. A fruitful thought must have its roots in the processes of development that mankind as a whole has to undergo in the course of its historical evolution. Whoever intends to depict the history of the evolution of philosophical thought from any kind of viewpoint can, for this purpose only, rely on such thoughts as are demanded by life itself. They must be thoughts that, when carried into the conduct of life, will penetrate man in such a way that he gains from them energies capable of directing his knowledge. They must become his advisors and helpers in the task of his existence. Because mankind needs such thoughts, philosophical world views have come into existence. If it were possible to master life without them, man would never have been inwardly justified to think of the Riddles of Philosophy. An age that is unwilling to think such thoughts shows through this fact merely that it does not feel the need to form human life in such a way that it can really unfold itself in all directions according to its original destination. But for such a disinclination, a heavy penalty must be paid in the course of human evolution. Life remains undeveloped in such ages, and men do not notice their sickly state because they are unwilling to recognize the demands that nevertheless continue to exist deeply seated within them and that they just fail to satisfy. A following age shows the effect of such a neglect. The grandchildren find in the formation of a stunted life something that was caused by the omission of the grandparents. This omission of the preceding age has turned into the imperfect life of the later time into which the grandchildren find themselves placed. In life as a whole, philosophy must rule. It is possible to sin against this demand, but it is inevitable that this sin will produce its effects.
We shall only understand the course of the development of philosophical thought, the existence of the Riddles of Philosophy, if we have a feeling for the significance that the philosophical contemplation of the world possesses for a whole, full human existence. It is out of such a feeling that I have written about the development of the riddles of philosophy. I have attempted to show through the presentation of this development that such a feeling is inwardly justified.
Against this feeling there will emerge from the outset in the minds of some readers a certain dampening objection that at first sight seems to be based on fact. Philosophical contemplation is supposed to be a necessity of life, but in spite of this, the endeavor of human thought in the course of its development does not produce clear-cut and well-defined solutions to the riddles of philosophy. Rather are they ambiguous and apparently contradictory. There are many historical analyses that attempt to explain the only too apparent contradictions through superficially formed ideas of evolution. They are not convincing. To find one's way in this field, evolution must be taken much more seriously than is usually the case. One must arrive at the insight that there cannot be any thought that would be capable of solving the riddles of the universe once and for all times in an all-comprehensive way. Such is the nature of human thinking that a newly found idea will soon transform itself in turn into a new riddle. The more significant the idea is, the more light it will yield for a certain time; the more enigmatic, the more questionable it will become in a following age.
Whoever wants to view the history of human thought development from a fruitful point of view must be able to admire the greatness of an idea in one age, and yet be capable of producing the same enthusiasm in watching this idea as it reveals its shortcoming in a later period. He must also be able to accept the thought that the mode of thinking to which he himself adheres will be replaced in the future by an entirely different one. This thought must not divert him from recognizing fully the truth of the view that he has conquered for himself. The disposition of mind that is inclined to believe that thoughts of an earlier time have been disposed of as imperfect by the perfect ones of the present age, is of no help for understanding the philosophical evolution of mankind.
I have attempted to comprehend the course of human thought development by grasping the significance of the fact that a following age contradicts philosophically the preceding one. In the introductory exposition, Guiding Thoughts of the Presentation, I have stated which ideas make such a comprehension possible. The ideas are of such a nature that they will necessarily find a great deal of resistance. At first acquaintance they will have the appearance of something that just occurred to me and that I now wanted to force in a fantastic manner on the whole course of the history of philosophy. Nevertheless, I can only hope that one will find that the ideas are not thought up as preconceived and then superimposed on the view of philosophical development, but that they have been obtained in the same way in which the natural scientist finds his laws. They have their source in the observation of the evolution of philosophy. One has no right to reject the results of an observation because they are in disagreement with ideas that one accepts as right because of some kind of inclination of thought without observation. Opposition to my presentation will be based on the superstitious denial of the existence of forces in human history that manifest themselves in certain specific ages, and dominate effectively the development of human thought in a meaningful and necessary way. I had to accept such forces because the observation of this development had proved their existence to me, and because this observation made apparent to me the fact that the history of philosophy will only become a science if one does not shrink back from recognizing forces of this kind.
It seems to me that it is only then possible to gain a tenable attitude toward the riddles of philosophy, fruitful for life at the present time, if one knows the forces that dominated the ages of the past. In the history of thought, more than in any other branch of historical reflection, it is necessary to let the present grow out of the past. For in the comprehension of those ideas that satisfy the demand of the present, we have the foundation for the insight that spreads the right light over the past. The thinker who is incapable of obtaining a philosophical viewpoint that is adequate to the dominating impulses of his own age will also be unable to discover the significance of the intellectual life of the past. I shall here leave the question undecided whether or not in some other field of historical reflection a presentation can be fruitful that does not at least have a picture of the present situation in this field as a foundation. In the field of the history of thought, such a procedure would be meaningless. Here the object of the reflection must necessarily be connected with the immediate life, and this life, in which thought becomes actual as practice of life, can only be that of the present.
With these words I have meant to characterize the feeling out of which this presentation of the riddles of philosophy grew. Because of the short time since the last edition, there is no occasion for change or additions to the content of the book.