220 COLLECTIVE REVIEWS
process. Even sensation is no mere 'impression' of an outer stim- ulus. In the absence of stimuli, the activity of the waking state produces a 'sensory negation', i. e. a sensory judgement to the effect that there is silence, etc. When a stimulus is applied, the (inner) activity of the waking state changes from the previous condition to the new one occasioned by the presence of the stimulus. The sensation itself is due to this process of (inner) change. We have to assume the existence of a spontaneous walcing instinct and a corresponding desire to be awake, i. e. a 'walcefulness'; this wake- fulness seeks to prevent the physical effect of the stimulus within the organism by opposing to it a certain counter-tendency. Sen- sation corresponds to a counter-active and adaptive process on the part of the organism. Generalisation and abstraction are like- wise processes of self-preservation and adaptation. Sleep also is an active process — in this case practice (practice in simple preserva- tion of the Ego); being awake is a state of adapted sleep. Piklef's ideas show a certain parallelism to those of psycho-analysis; thus the idea of wakefulness keeping watch at the portals by which the stimuli enter and of being alert or strained at these points may perhaps be regarded as corresponding to the notion of 'charge'.
It is well known that about twenty years ago Ranschburg set up a new 'fundamental neuropsychic law' which was based on the fusion of the effects of simultaneous stimuli. Henning (15) now ^ gives an experimental disproof of tliis law — a law which was used by its originator to oppose the Freudian explanations. Henning considers that the explanation of the fact that identical elements often exercise a disturbing influence on one another is to be found in the diminished reciprocity of the 'residual components' in these cases, ftenning in his review on 'Applied Psychology' complains that Erisman in dealing with the subject of mistakes refers to Freud's theory and not to his (Henning's) theory of 'residual com- ponents'. Now it appears from Henning's protocols that his subjects experienced marked 'pain' when confronted with homologous series of stimuli (i. e. series containing identical members). This naturally inclines us to raise the question whether Ranschburg's principle is not reducible to the consequences of 'pain'.
The effect of 'pain' is also demonstrated, by the work of Spielrein (30), in the case of arithmetical operations. For reasons connected with the actual process of calculation itself certain figures acquire an unpleasant feeling tone, which manifests itself
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