It is to him of great moment that his readers shall not believe in the existence of the thinking and feeling _Ego_ as a person, apart from the organic mechanism which conveys impressions and presentations to the _Ego_. He uses all the arguments which that school of thinkers to which he belongs has piled up in order to show that mind is a condition of matter. He says nothing about the arguments on the other side, but treats them as the science of the past. He takes for granted, without showing a vestige of doubt, that human beings are nothing but organic mechanisms. He does not even refer to, or allow that there is, anything beyond the present scientific discoveries, and scornfully ignores the existence of what less prejudiced scientists call the Unknowable. He thus treats a question which still trembles in the balance as if it were already decided in favour of his pet theories. The attitude which biologists and psychologists take up as such, and with the special purpose of proceeding in their investigations with perfectly unbiassed minds, Nordau assumes as a philosopher, and tries to persuade himself and others that he has taken his stand on absolute facts. Science proceeds on the supposition that only that is true which has been proved so by demonstrations to our senses, or through deductions from such demonstrations. This, of course, is a postulate the illogicality of which most scientific men are aware of, and is adopted mostly for the purpose, as it were, of clearing the ground. To assume, apart from their investigating attitude, that there is nothing more to know than what is already known, would be an utterly absurd assumption, as it would, if acted upon, preclude further investigation. Nordau does not, and would not, deny that there is more to learn, but he persists in the view that all future knowledge will be on the lines of our present knowledge, and never contradictory to the present prevailing scientific dogmas. He remains under this impression, because he forgets that science has progressed, progresses, and, as far as we see now, always will progress through investigations by our senses, and that this fact brings two important truths conspicuously into relief. The first, that our senses are liable to deceive us, and that consequently the difference between primitive views—the result of imperfect observation—and the scientific opinions of the day is not one of kind, but simply one of degree. In olden times the senses deceived us very much, and nowadays they deceive us less. But to what an extent they deceive us now the future alone can reveal. The second, that science with the present methods cannot investigate anything that does not appeal to our senses.