Man needs to give himself a perspective on nonknowledge in the form of death. Bataille
To 'realize' the concept of nothingness is not to see nothingness but to die. Levinas
There is an absolutely obvious, normal step, almost a command, a silent requirement to do what we should do in order to secure and improve our life. We want to succeed, to achieve something in this world. Our thinking, perceiving, behaving are shaped by a belief in (improvement of our) life which guides us in our daily activities, in our moral and political attitudes. An alive thinking is consolidated on and on and this alive, healthy thinking constantly forms us as healthy, functional humans. And as humans we want that a healthy, alive world take shape around our healthy habits.
William James witnessed how healthy thinking became a new religion or at least a new background for old religions in the middle of the 19th century when the advance of liberalism brought about 'a victory of healthy-mindedness' over the morbidity of the old 'hell-fire theology'. Healthy-mindedness believes in universal evolution, 'general meliorism', progress and appreciates 'the conquering efficacy of courage, hope, trust'. Healthy-mindedness fosters an optimistic 'muscular attitude', similar to the one implicit in 'Don't Worry Movement' which has a motto that one is encouraged to repeat to oneself often: 'youth, health, vigor!'. But healthy-mindedness brings also contempt: for doubt, fear, worry, and 'all nervously precautionary states of mind'. For a healthy mind 'the attitude of unhappiness is not only painful, it is mean and ugly'. It is impossible to maintain this healthy-mindedness without 'zealously emphasizing the brighter and minimizing the darker aspects of the objective sphere of things at the same time. . .we divert our attention from disease and death as much as we can; and the slaughter-houses and indecencies without end on which our life is founded are huddled out of sight and never mentioned.'(1)
Healthy thinking avoids morbidity and tries to be optimistic but this doesn't matter too much, the morbidity is in the world itself - we may abandon morbidity but morbidity is not abandoning us. We believe in life and we are attached to the features of this world, but this world is doomed, we are doomed. As we all know death is much more powerful than life, at least we feel it if we don't think it. But death is not just a personal problem anymore, we are in an era of death, in a dying world. Now we know that we are in the middle of the extinction - we are in the quickest species extinction period, faster than when dinosaurs were extinct, facing climate change, imminent resource depletion, catastrophic economic disorder, etc. This planetary decline affects our modes of perceiving, thinking and feeling, we somehow register these changes and we are affected even (or especially) if we are not aware. But if we are not aware maybe there is a reason for that, apart from the tendency of healthy thinking to protect itself from disturbing thoughts.