An ordinary person does not kill himself because of a mathematical problem, nor because he misunderstands thermodynamics. Maybe a physicist does, provided that such a problem, for him, takes on an existential dimension. But the common person, just like the physicist, kills himself after a great financial or affective loss, or after a romantic disappointment. We can see, here, a common trait between both, or a problem that affects both. This problem, exposed in the most varied ways, is the central problem of human existence. And I have to notice, among all the most brilliant minds in history, my predilection for those who were able to see it.