Idealist philosophers are apt to say that the subject alone is known to us, while the existence of the object must forever remain a vague hypothesis. This, however, is incorrect. It involves an unjustifiable deprecation of the objective element in the given facts of conscious states, and is based on a misconception of the entire state of things. The data of knowledge are not mere subjective states, they are relations between subject and object. Neither the subject is given, nor the object; but an interaction between subject and object. From this interaction we derive by a very complicated process of abstraction both concepts, the subject as well as the object. It is true that the subjective world of feelings and of representative feeling is very different from the objective world of things. Nevertheless they are one. The subject together with all objects forms one inseparable whole of subject-object-ness. Every special object, accordingly, must be conceived as a part of this inseparable whole—of the All; it is a certain set of facts, represented in a certain group of experiences, and is to be described as that something which in a special way affects the subject and can again in a special way be reacted upon by the subject. #Idealism and realism.# Here we have the clue for the proper meaning of objectivity. What is a piece of lead but something that at a definite distance from the centre of the earth exerts a certain pressure proportionate to its mass; that is seen to become liquid at a certain temperature; etc., etc.? If it is treated in a particular way, it will be observed to suffer certain changes. What lead is has been established by experience; i. e., by systematic observation through sense-impressions. From this standpoint the differences between the schools of idealism and realism appear as antiquated. The questions whether matter is real, whether objects exist, and whether there is any reality at all, have lost their meaning. That which produces effects upon the subject and against which the subject does or can react, is called object. The sense-effects produced by the object upon the subject, and also the reactions of the subject upon the object, are realities; and every name of a special object signifies a certain group of such effects and their respective reactions. Thus, for instance, the word lead comprises a certain set of experiences that have always been found combined with certain whitish objects. #Space and Reality.#