So far the psychologists have not even started to examine these economic feelings, demands, and satisfactions with the means of laboratory psychology. Hence no one can say beforehand how it ought to be done and how to gain access to the important problems, inasmuch as the right formulation of the problem and the selection of the right method would here as everywhere be more than half of the solution. It must be left to the development of science for the right starting-point and the right methods to be discovered. Sometimes, to be sure, the experiment has at least approached this group of economic questions. For instance, the investigations of the so-called psychophysical law have often been brought into contact with the experiences of ownership and acquirement. The law, well known to every student of psychology, is that the differences of intensity in two pairs of sensations are felt as equal, when the two pairs of stimuli are standing in the same relation. The difference between the intensities of the light sensations from 10 candles and 11 candles is equal to that from 50 candles and 55 candles, from 100 candles and 110, from 500 candles and 550: that is, the difference of one additional candle between 10 and 11 appears just as great as the difference of 50 candles between 500 and 550. The psychologists have claimed that in a corresponding way the same feeling of difference arises when the amounts of possessions stand in the same relation. That is, the man who owns $100 feels the gain or loss of $1 as much as one who owns $100,000 feels the gain or loss of $1000. Not the absolute amount of the difference, but the relative value of the increase or decrease is the decisive influence on the psychological effect. Some experimental investigations concerning feelings have also come near to the economic boundaries. The study of the contrast feelings and of the relativity of feelings, for instance, has points of contact with the economic problem of how far economic progress, with its stirring up and satisfying of continually new demands, really adds to the quantity of human enjoyment. In other words, how far are those sociologists right who are convinced that by the technical complexity of modern life, with all its comforts and mechanizations, the level of individual life is raised, but that the oscillations about this average level remain the same and produce the same amount of pleasure and pain? The technical advance would therefore bring no increase of human pleasure.