Nostalgia can be a bitter poison if you believe the world is getter worse. Optimistic people try to point out the many ways in which our lives are better only to find poisoned barbs dipped in statistics of all ways things are worse.
That poison absorbs into our frail hearts when aimed well. I see how things are worse just as well as any pessimist. Choosing optimism requires us to find antidotes to those poisons, lest we have a full blown case of what the French call “Ressentiment”
It is a terrible disease. Ressentiment literally translates to the English resentment but rancœur (bitterness), amertume (acrimony), and animosité (ill-will) are all part of its dangerous pathology.
Nietzschean scholars will note he meant it specifically as an emotion of feeling of deep-hostility towards those who make you believe you are powerlessness.
In his Genealogy of Morals, Nietzsche sketched out how this feeling of weakness justifies and creates value systems as a defense mechanism of the ego. Rather than overcome these feelings, the ego insulates you in a value system where one never need address real failures or weaknesses.
There is much to criticize in his work, and I am not a Nietzschean myself. But it’s easy to see how much we all live in jealousy and inferiority from time to time. Some of us live there always.
Many moral systems raise up the weak in virtue in order to protect them. Christianity is one of them. There is value in protecting and improving the lowest of us even if I disagree that we should see the powerful as morally inferior. Power and strength and beauty are virtues as well.
As we envy the past or those whose past decisions made our present lives harder we must be cautious that we have not absorbed the poison of ressentiment. Do not justify harm in its name. Do not justify jealousy or envy. Rise up and spit out that poison. Our world can be better and you can be better as you work towards that goal.