But these three moments in consciousness have their correlatives in the modifications of the organism: circulation, respiration, motion, the various phases of nutrition. The first answers to the average vital formula of the individual; the second to an increase in the vital functions, and, according to the usual formula (which we shall examine later on), to an augmentation of energy; the third to a lowering of the vital functions and a diminution of energy. Such are the data of observation and experience. Féré’s researches on the olfactory sensations (to mention no others) have shown that the feelings accompanying them, pleasant or otherwise, show themselves in an augmented or diminished pressure on the dynamometer. In a subject whose dynamometric force is normally 50-55, a disagreeable odour lowers the index to 45, an agreeable one raises it to 65. In another (a hysterical patient) the odour of musk, at first very pleasant, raises the dynamometer from 23 to 46; in three minutes it becomes disagreeable, and the pressure sinks to 19.[38] We find, therefore, that the organism is subject to perpetual fluctuations, indicated in the consciousness by agreeable or disagreeable feelings: the two opposites are connected with one and the same cause, the vital functions forming their common basis; and I should be inclined to propound the following hypothesis:— Footnote 38: Féré, _Sensation et Mouvement_, pp. 62, 63. In most cases, if not in all, two contrary processes are going on simultaneously—one of increase, the other of diminution; _what comes into the consciousness is only the result of a difference_. A difference between what? Between receipt and expenditure. Let us, in order to show this clearly, take a point at which the destructive and constructive activities exactly balance one another, a condition corresponding to the neutral or indifferent state of psychologists, and let us represent the same by the numerical formula 50 = 50. At a subsequent point of time the destructive activities predominate; let us suppose them equal to 60, while the value of the constructive falls to 40. On comparing the second moment with the first, we find a negative difference of -20, whose psychic equivalent is a painful state of consciousness. Let us then suppose a third moment, when the constructive activities are in the ascendent and equal 60, while the destructive fall to 40; there will be a positive difference of +20, whose psychic equivalent is a pleasant state of consciousness. I must beg the reader to take all this only by way of illustration.