Experiments are not to be despised; but as for the figure supposed to illustrate the phenomenon, it is merely misleading; this mathematical conception explains nothing. The assimilation of pleasure to a positive, and pain to a negative value, is quite arbitrary. Moreover, the passage from _plus_ to _minus_ quantities through zero is an operation which has its base in our faculty of abstraction, and for its materials abstract and homogeneous quantities. The different degrees of pleasure and pain are nothing of this sort. We do not even know if these two phenomena have a common foundation, if there is a common measure between the two, if they are not both irreducible, and we have no right to place, theoretically, a _Nullpunkt_ at the point of transition from one to the other. The problem is one of a concrete order; it is a question of fact, whether soluble or not, which is put before us. 2. Let us now listen to those who refuse to admit states of indifference. Every state of consciousness is a trinity in the theological sense: it is the knowledge of some exterior or interior event; it includes motor elements; it has a certain tone of feeling. We describe it as intellectual, motor, or emotional, according to the preponderance of one of these elements, not its exclusive existence. It is a well-known fact that the clearer a perception, the weaker is its tone of feeling, and the more intense an emotion, the more attenuated the intellectual element which has evoked it; but diminution is not equivalent to disappearance. If neutral states existed, one of the fundamental elements of psychic life would exist only in an intermittent form, and at some moments even cease to be. Besides this, let us observe ourselves and interrogate our own consciousness. “Let us consider ourselves at one of those moments of calm and apparent indifference, when it seems as if nothing could move us, and our numbed sensibility remains, as it were, suspended between pleasure and pain. This deceptive appearance of insensibility and aridity always masks some more or less feeble sensations of ease or uneasiness, some more or less slight and confused sentiments of joy or grief which are none the less real for being in nowise vivid or exciting. Moreover, how could our sensibility fail to be, constantly, more or less impressed by so many general causes which, independent of particular causes, so constantly act upon us, at every instant of our life, and which, so to speak, ceaselessly besiege us, from within and from without?” Bouillier, the author of this passage (_op. cit._, chap. xi.), supports his assertions by citing the innumerable impressions which come from the internal organs, from the state of the air and sky, from light, from the most trivial incidents of common life.