Other special circumstances influence even more this precocious satiety of life. As I become more indifferent to my own life I feel a more and more acute anxiety for the health, life, and happiness of those who are dear to me.
I am especially troubled by a consciousness of the imperfection of modern medicine. In spite of the progress realised in these latter days, it is still powerless against a multitude of diseases, threatening us on all sides.
Pulmonary lesions (tuberculosis, pneumonia, etc.), the nephrites, and an infinite quantity of other diseases can yet neither be prevented nor cured. So we live in constant fear for those we love. When medicine shall (as I am persuaded) have conquered all these evils, one cause of the bitterness of life will cease—but that is not yet the case.
That is why, besides the weakening of the life-instinct, a resignation towards death grows in us, as a means of no longer feeling the ills which afflict our neighbours.
With time, when that source of unhappiness has been eliminated by medicine, old age will be more attractive, and an orthobiotic life will become normal and realisable.
At the ages of 50, 60, 65, I felt an intense joy in living, such as I described in my Studies on Human Nature and Optimistic Essays. In the last few years it has lessened markedly.
Scientific work still provokes in me an invincible enthusiasm, but I am becoming more indifferent to many of the pleasures of life.
And indeed he no longer had the joyous soul of former days; into his life a funereal note had crept, low but continuous and obstinate. He gave all the more energy to the study of those questions the solution of which was to bring about the reign of orthobiosis. He spent the whole winter in researches on the intestinal flora and on the completion of his studies on infantile cholera.
In the spring, on the occasion of his anniversary, he wrote the following:
Sèvres, 16th May 1914.