[18] I expressed this thought many years ago (in the _Vierteljahrsschrift für Psychiatrie_, Leipsic and Neuwied, 1868: _Ueber die Abhängigkeit der Netzhautstellen von einander_) as follows: The expressions "sense-deception" and "illusion of the senses" prove, that we are not yet fully conscious, or at least that we have not yet found it necessary to incorporate this consciousness into our ordinary terminology, _that the senses represent things neither wrongly nor correctly_. All that can be truly said of the sensory organs is, that, _under different circumstances they produce different sensations and perceptions_. Since these "circumstances" are of so extremely manifold a character, being partly external (inherent in the objects), partly internal (inherent in the sensory organs), and partly interior (having the seat of their activity in the central organs), it would naturally seem, especially when attention is paid only to external circumstances, that an organ acts differently under like conditions. And it is customary to call the unusual effects, deceptions or illusions. We see an object with a point _S_. If we touch _S_, that is bring it into relation with our body, we receive a prick. We can see _S_, without feeling the prick. But as soon as we feel the prick we find _S_. The visible point therefore is a _permanent fact_ or _nucleus_, to which the prick is annexed, according to circumstances, as something accidental. From the frequency of occurrences analogous to this we ultimately accustom ourselves to regard _all_ properties of bodies as "effects" proceeding from permanent persistent nuclei and conveyed to the ego through the mediation of the body; which effects we call _sensations_. By this very operation, however, these imagined nuclei lose their entire sensory content, and become mere mental symbols. The assertion is correct then that the world consists only of our sensations. In which case we have knowledge _only_ of sensations, and the assumption of the nuclei mentioned, as well as of a reciprocal action between the same, from which sensations might be supposed originally to proceed, turns out to be wholly idle and superfluous. Such a view can only suit a halting realism or a half-matured philosophic criticism. VI. Ordinarily the complex α β γ ... _K L M_ ... is opposed as ego to the complex _A B C_. Those elements only of _A B C_ ... that more actively alter α β γ ..., as a prick, a pain, are we accustomed to comprehend in the ego. Afterwards, however, through observations of the kind above mentioned, it appears that the right to annex _A B C_ ... to the ego at no point ceases. In conformity to which the ego can be so extended as ultimately to comprehend the entire world. * * * * *