is self-contradictory, is not." [42] According to E. L. Fischer, knowledge is the science of something actual, something real, [43] and he criticises this dogma as little as does Goering who asserts similarly, "To know means always to know something which is. This is a fact which cannot be denied either by scepticism or by Kant's critical philosophy." [44] These two latter thinkers simply lay down the law: This is what knowledge is. They do not trouble to ask themselves with what right they do it. But, even if these various propositions were correct, or led to correct formulations of the problem, it would still be impossible to discuss them at the outset of the Theory of Knowledge. For, they all belong, as positive and definite cognitions, within the realm of knowledge. To say that my knowledge extends, in the first instance, only to my ideas, is to express in a perfectly definite judgment something which I know. In this judgment I qualify the world which is given to me by the predicate "existing in the form of idea." But how am I to know, prior to all knowledge, that the objects given to me are ideas? The best way to convince ourselves of the truth of the assertion that this proposition has no right to be put at the head of the Theory of Knowledge, is to retrace the way which the human mind must follow in order to reach this proposition, which has become almost an integral part of the whole modern scientific consciousness. The considerations which have led to it are systematically summarised, with approximate exhaustiveness, in Part I of Eduard von Hartmann's treatise, Das Grundproblem der Erkenntnistheorie. His statement, there, may serve as a sort of guiding-thread for us in our task of reviewing the reasons which may lead to the acceptance of this proposition. These reasons are physical, psycho-physical, physiological, and properly philosophical.