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.