ON LIFE-SA TISFA CTION 683
proved as well by history as by our observations of ourselves and our surroundings. The historical examples of Greece and Rome are familiar to all. A generally hopeful state of mind existed there precisely at the epoch of the most intensive elabo- ration of different problems or of the most extensive growth of territory, and not at the period when inventions and discoveries had already been made or territories acquired ; in other words, not at the time when the people could enjoy the goods already acquired ; on the contrary, just at this epoch a feeling of discon- tent and pessimism prevailed.
It is interesting to note that nations instinctively feel this. It is always at a definite stage of progress that regrets commence about a pastoral life, about a past golden age, etc. All this is only a reminiscence of times when progress was more rapid and when every day brought something new into life.
Similarly individuals like to remember their youth, although they were then, no doubt, less intellectual and probably poorer than at a later age. But their " progress curve " formed a large angle with the abscissae axle, the quantity of goods they pos- sessed increased very rapidly, and this overcame all. One learns in his youth that the square of the hypothenuse is equal to the sum of the squares of the two other sides of the triangle ; he learns wonderful laws of the movement of celestial bodies, beautiful chemical formulas, the principle of evolution of living creatures. A youth feels for the first time the emotions of love ; for the first time he tries to say "yes" and "no" in his own business affairs, insignificant though they be. But all this passes quickly in a few years.
Later the individual learns more about the laws of nature. He is now able to love better women than before, to accomplish more important and more difficult tasks. But, in spite of this, there is at this stage no such intensity of life ; the curve ascends slowly, and there is thus less contentment than before. Every -
dG
symbol signifies the relative increase of the quantity G with the time t; the
symbol / means function or dependence ; so that the above formula can be expressed in words as follows : The degree of life-satisfaction (S) is depending (/) upon the relative growth of the goods possessed (dG) with the time (dt).
