Systematization is the essence and the general expression of the aggregate activity of science. Science seeks to classify and systematize the objects of the world for the understanding of our brain. The scientific understanding of a certain language, e. g., requires an orderly arrangement of that language in general categories and rules. The science of agriculture does not simply wish to produce a good crop of potatoes, but to find a system for the methods of cultivation and thus to furnish the knowledge by which success in cultivation can be determined beforehand. The practical result of all theory is to acquaint us with the system and method of its practice and thus to enable us to act in this world with a reasonable certainty of success. Experience is, of course, an indispensable condition for this purpose; but it alone is not sufficient. Only by means of empirically developed theories, by science, do we overcome the play of accident. Science gives us the conscious domination over things and unconditional security in handling them.

No one individual can know everything. The capacity of the individual brain is no more adequate for the knowledge of everything that is necessary than the skill and strength of the individual's hands are sufficient to produce all he needs. Faith is indispensable to man, but only faith in that which others know, not in what they believe. Science is as much a social matter as material production. "One for all and all for one."

But just as there are some wants of the body which every one has to satisfy by himself, so every one has to know certain scientific facts which are not the prerogative of any special science.

This is true of the faculty of human understanding. The knowledge and study of this theory cannot be left to any particular guild. Lassalle justly says: "Thinking itself has become a special trade in these days of division of labor, and it has fallen into the worst hands, those of our newspaper writers." He thus urges us not to acquiesce in this appropriation any longer, not to submit any more to the harangues of public opinion, but to resume thinking for ourselves. We may leave certain objects of scientific research to professionals, but general thought is a public matter which every one should be required to attend to himself.

If we could place this general work of thinking on a scientific basis, if we could find a theory of general thought, if we were able to discover the means by which reason arrives at understanding, if we could develop a method by which truth is produced scientifically, then we should acquire for science in general and for our individual faculty of judgment the same certainty of success which we already possess in special fields of science.

Kant says: "If it is not possible to harmonize the various co-operators on the question of the means by which their common aim is to be accomplished, then we may safely infer that such a study is not yet on the secure road of science, but will continue to grope in the dark."

Now, if we take a look at the sciences, we find that there are many, especially among the natural sciences, which fulfill the requirements of Kant, agreeing unanimously and consciously on certain empirical knowledge and building further understanding on that. "There we know," as Liebig says, "what is to be called a certain fact, a conclusion, a rule, a law. We have touchstones for all this, and every one makes use of them before making known the fruits of his labors. The attempt to maintain any proposition by lawyer's tricks, or the intention to make others believe anything that cannot be proven, are immediately wrecked by the ethics of science."

Not so in other fields, where concrete and material things are left behind and abstract, so-called philosophical, matters are taken up, as, for instance, questions of general conceptions of the world and of life, of beginning and end, of the semblance and the essence of things, of cause and effect, of matter and force, of might and right, of wisdom of life, of morality, religion, and politics. Here we find, instead of irrefutable proofs, mere "lawyer's tricks," an absence of reliable knowledge, a mere groping amid contradictory opinions.

And it is precisely the prominent authorities of natural science who show by their disagreements on such matters that they are mere tyros in philosophy. It follows, then, that the socalled ethics of science, the touchstones of which the boast is made that they never fail in determining what is knowledge and what is mere conjecture, are based on a purely instinctive practice, not on a conscious theory of understanding. Although our time excels in diligent scientific research, yet the numerous differences among scientists show that they are not capable of using their knowledge with a predetermined certainty of success. Otherwise, how could misunderstandings arise? Whoever understands understanding, cannot misunderstand. It is only the absolute accuracy of astronomical computations which entitles astronomy to the name of a science. A man who can figure is at least enabled to test whether his computation is right or wrong. In the same way, the general understanding of the process of thought must furnish us with the touchstone by which we can distinguish between understanding and misunderstanding, knowledge and conjecture, truth and error, by general and irrefutable rules. Erring is human, but not scientific. Science being a human matter, errors may exist eternally, but the understanding of the process of thought will enable us quite as well to prevent errors from being offered and accepted as scientific truths as an understanding of mathematics enables us to eliminate errors from our computations.

It sounds paradoxical and yet it is true: Whoever knows the general rule by which error may be distinguished from truth, and knows it as well as the rule in grammar by which a noun is distinguished from a verb, will be able to distinguish in both cases with equal certainty. Scientists as well as scribes have ever embarrassed one another by the question: What is truth? This question has been an essential object of philosophy for thousands of years. This question, like philosophy itself, is finally settled by the understanding of the faculty of human thought. In other words, the question of what constitutes truth is identical with the question of the distinction between truth and error. Philosophy is the science which has been engaged in solving this riddle, and the final solution of the riddle by the clear understanding of the process of thought also solves the question of the nature of philosophy. Hence a short glance at the nature and development of philosophy may well serve as an introduction to our study.

As the word philosophy is connected with various meanings, I state at the outset that I am referring only to socalled speculative philosophy. I dispense with frequent quotations and notes of the sources of my knowledge, as anything that I may say in this respect is so well established that we can afford to discard all scientific by-work.

If we apply the above-named test of Kant to speculative philosophy it appears to be more the playground of different opinions than of science. The philosophical celebrities and classic authorities are not even in accord on the question: What is philosophy and what is its aim? For this reason, and in order not to increase the difference by adding my own opinion, I regard everything as philosophy that calls itself by that name, and we select from the voluminous literature of philosophy that which is common and general in all philosophers, without taking any notice of their special peculiarities.

By this empirical method we find first of all that philosophy is originally not a specialized science working with other sciences, but a generic name for all knowledge, the essence of all science, just as art is the essence of the various arts. Whoever made knowledge, whoever made brain work his essential occupation, every thinker without regard to the contents of his thoughts, was originally a philosopher.

But when with the progressive increase of human knowledge, the various departments detached themselves from the mother of all wisdom, especially since the origin of natural sciences, philosophy became known, not so much by its content as by its form. All other sciences are distinguished by their various objects, while philosophy is marked by its own method. Of course, it also has its object and purpose. It desires to understand the universal whole, the cosmos. But it is not this object, this aim, by which philosophy is characterized; it is rather the manner in which this object is accomplished.

All other sciences occupy themselves with special things, and if they consider the universe at all, they do so only in its bearing on the special objects of their study, the parts of which the universe is composed. Alexander von Humboldt says in his introduction to his "Cosmos" that he is limiting himself to an empirical consideration, to a physical research, which seeks to elucidate the uniformity and unity by means of the great variety. And all inductive sciences arrive at general conclusions and conceptions only by way of their occupation with special and concrete things. For this reason they claim that their conclusions are based on facts.

Speculative philosophy proceeds by the opposite method. Thought, the object of its study, may be some special question, yet it does not follow this up in the concrete. It rejects as fallacious the evidence of the senses, the physical experience gained by means of the eye and ear, hand and brain, and limits itself to "pure" and absolutely abstract thought, in order to understand thus by the unit of human reason the multiplicity of the universe. In seeking for an answer to the question: What is philosophy? which question we are specially discussing just now, speculative philosophy would not start out from its actual material form, from its wooden and pigskin volumes, from its great and small essays, in order to arrive at a conception of its object. On the contrary, the speculative philosopher turns to introspection and looks in the depths of his own mind for the true concept of philosophy. And by this standard he separates the impression of his senses into true or erroneous. This speculative method has hardly ever dealt in tangible things, unless we recognize this philosophical method in every unscientific concept of nature which populated the world with spooks. The rudiments of scientific speculation occasionally dealt with the course of the sun and the globe. But since inductive astronomy cultivates these fields with greater success, speculative philosophy limits itself entirely to abstract discussions. And in this line of research as well as in all others it is characterized by the production of its results out of the idea or the concept.

For empirical science, for the inductive method, the multiplicity of experiences is the first basis, and thought the second. Speculative philosophy, on the other hand, seeks to arrive at scientific truth without the help of experience. It rejects the socalled transient facts as a foundation of philosophical understanding, and declares that it should be absolute, exalted above time and space. Speculative philosophy does not wish to be scientific physics, but metaphysics. It regards it as its task to find by "pure" reason, and without the assistance of experience, a system, a logic, or a theory of science, by which everything worth knowing is supposed to be reeled off logically and systematically, in about the same way in which we derive grammatically the various forms of a word from its root. But the physical sciences operate on the assumption that our faculty of understanding, to use a familiar illustration, resembles a piece of soft wax which receives impressions from outside, or a clean slate on which experience writes its lines. Speculative philosophy, on the other hand, assumes that certain ideas are innate and may be dipped and produced from the depths of the mind by means of thought.

The difference between speculative and inductive science is that between fantasy and sound common sense. The latter produces its ideas by means of the outer world, by the help of experience, while fantasy gets its product from the depth of the mind, out of itself. But this method of production is only seemingly one-sided. A thinker can no more think transcendental thoughts which are beyond the reach of experience, than a painter can invent transcendental pictures, transcendental forms. Just as fantasy creates angels by a combination of man and bird, or mermaids by a composition of woman and fish, so all other products of fantasy, though seemingly derived out of itself, are in fact only arbitrarily arranged impressions of the outer world. Reason operates with numbers and orders, time and measures, and other means of experience, while fantasy reproduces the experiences without regard to law and in an arbitrary form.

The longing for knowledge has been the cause of speculative attempts to explain the phenomena of life and nature at a time when lack of experience and observation made inductive understanding impossible. Experience was then supplemented by speculation. In later times, when experience had grown, previous speculation was generally recognized as erroneous. But it nevertheless required thousands of years of repeated disappointments on one side and numerous brilliant successes of the inductive method on the other, before these speculative hobbies came into disfavor.

Fantasy has certainly a positive power, and speculative intuition, derived from analogy, very often precedes empirical and inductive understanding. But we must remain aware of the fact that so much is assumption and so much actual scientific knowledge. Conscious intuition stimulates scientific research, while pseudo-science closes the door to inductive research. The acquisition of the clear understanding of the distinction between speculation and knowledge is a historical process, the beginning and end of which coincides with the beginning and end of speculative philosophy.

In ancient times, common sense operated in common with fantasy, the inductive with the speculative method. The discussion of their differences begins only with the understanding of the numerous disappointments caused by the still inexperienced judgment which have prevented an unobstructed view of the question up to modern times. But instead of attributing these disappointments to lack of understanding, they were charged to the account of the imperfection of the senses. The senses were called impostors and material phenomena untrue images. Who has not heard the lament about the unreliability of the senses? The misunderstanding of nature and of its phenomena led to a serious rupture with sense perceptions. The philosophers had deceived themselves and thought they had been deceived by the senses. In their anger they turned disdainfully away from the world of sensations. With the same uncritical faith with which the semblance had hitherto been accepted as truth, now uncritical doubt rejected the truth of sensations altogether. Research abandoned nature and experience, and began the work of speculative philosophy by "pure" thought.

But no! Science did not permit itself to be entirely led astray from the path of common sense, from the way of truth of sense perceptions. Natural science soon stepped into the breach, and its brilliant successes gained for the inductive method the consciousness of its fertility, while on the other hand philosophy searched for a system by which all the great general truths might be opened up without specialized study, without sense perception and observation, by mere reason alone.

Now we have a more than sufficient quantity of such speculative systems. If we measure them with the aforementioned standard of unanimousness, we find that philosophy agrees only on its disagreements. In consequence, the history of speculative philosophy, unlike the history of other sciences, consists less of a gradual accumulation of knowledge, than of a series of unsuccessful attempts to solve the general riddles of nature and life by "pure" thought, without the help of the objects and experience of the outer world. The most daring attempt in this line, the most artificial structure of thought, was completed by Hegel in the beginning of the nineteenth century. To use a common expression, he became as famous in the world of science as Napoleon I did in the world of politics. But Hegelian philosophy has not stood the test of time. Haym, in his work entitled "Hegel and His Time," says of Hegelian philosophy that "it was pushed aside by the progress of the world and by living history."

The outcome of philosophy up to that time, then, was a declaration of its own impotence. Nevertheless, we do not underestimate the fact that a work occupying the best brains for thousands of years surely contained some positive element. And in fact, speculative philosophy has a history, which is not merely a series of unsuccessful attempts, but also a living development. However, it is less the object of its study, less the logical world system, which developed, than its method.

Every positive science has a material object, a beginning in the outer world, a premise on which its understanding is based. Every empirical science has for its fundament some material of the senses, some given object, on which its understanding is dependent, and thus it becomes "impure." Speculative philosophy seeks a "pure, absolute," understanding. It wishes to understand by "pure" reason, without any material, without any experience. It takes its departure from the enthusiastic conviction of the superiority of understanding and knowledge over experience gained by sense perceptions. For this reason it wishes to leave experience entirely aside in favor of absolutely "pure" understanding. Its object is truth; not concrete truth, not the truth of this or that thing, but truth in general, truth "in itself." The speculative systems seek after an absolute beginning, an indubitably self-supporting starting point, from which they may determine the absolutely indubitable. The speculative systems are thus by their own mentality perfectly complete and selfsufficient systems. Every speculative system found its end in the subsequent knowledge that its totality, its selfsufficiency, its absoluteness, was imaginary, that it could be determined empirically and externally like all other knowledge, that it was not a philosophical system, but a relative and empirical attempt at understanding. Speculation finally dissolved into the knowledge that understanding is by its very nature "impure," that the organ of philosophy, the faculty of understanding cannot begin its studies without a given point of departure, that science is not absolutely superior to experience, but only so far as it can organize numerous experiences. It followed from these premises that the object of philosophy can be a general and objective understanding, or "truth in itself," only in so far as understanding or truth in general can be derived from given concrete objects. In plain words, speculative philosophy was reduced to the unphilosophical science of the empirical faculty of understanding, to the critique of reason.

Modern conscious speculation takes its departure from the experienced difference between semblance and truth. It denies all sense phenomena in order to find truth by thinking, without being deceived by any semblance. The subsequent philosophers, however, found every time that the truths of their predecessors, gained by this method, were not what they pretended to be, but that their positive result consisted simply in having advanced the science of the thought process to a certain extent. By denying the actuality of the senses, by endeavoring to separate thought from all sense perceptions, by isolating it, so to say, from its sensory cover, speculative philosophy, more than any other science, laid bare the structure of the mind. The more this philosophy advanced in time, the more it developed in its historical course, the more classically and strikingly did this kernel of its work spring into view. After the repeated creation of giant fantasmagorias, it found its solution in the positive knowledge that socalled pure philosophical thought, abstracting from all concrete contents, is nothing but thoughtless thought, thought without any real object back of it, and produces mere fantasmagorias. This process of speculative deception and scientific exposure was continued up to recent times. Finally the solution of the main question, and the solution of speculation, was introduced with the following words of Feuerbach: "My philosophy is no philosophy."

The long story of speculative work was finally reduced to the understanding of reason, of the intellect, the mind, to the exposure of those mysterious operations which we call thinking.

The secret of the processes by which the truths of understanding are produced, the ignorance of the fact that every thought requires an object, a premise, was the cause of the idle speculative wanderings which we find registered in the history of philosophy. The same secret is today the cause of those numerous speculative mistakes which we observe in passing over the words and works of naturalists. Their knowledge and understanding is far developed, but only so far as it refers to tangible objects. The moment they touch upon abstract discussions, they offer "lawyers' proofs" in place of "objective facts." For although they know intuitively and in a concrete case that this is a truth, that a conclusion, and that a rule, they do not apply this knowledge in general with consciousness and theoretical consistency. The successes of natural science have taught them to operate the instrument of thought, the mind, instinctively. But they lack the systematic understanding which operates with conscious and predetermined certainty. They ignore the outcome of speculative philosophy.

It will be our task to set forth in a short summary what speculative philosophy has unconsciously produced of a positive nature by a tedious process, in other words, to explain the general nature of the thought process. We shall see that the understanding of this process will furnish us with the means of solving scientifically the general riddles of nature and of life. And thus we shall learn how that fundamental and systematic world conception is developed which was the long coveted goal of speculative philosophy.