Pessimism of the Intellect, Optimism of the Will.
Some recognize that it's a quote from Antonio Gramsci and mistakenly think it means I'm a Marxist.
In fact, the meaning of the slogan is quite simple.
Pessimism of the Intellect means, simply, be a scientist: see the world as it really is, not as you might like it to be. Try to identify and overcome hidden biases or prior assumptions. Always ask yourself: What assumption am I making? What if it is incorrect? How do I know what I know?
In many cases, the correct answer is: I don't know. Never be afraid to admit you don't know.
Optimism of the Will means, have the courage to attempt difficult things. Sometimes, Will can overcome the odds.
If people bring so much courage to this world the world has to kill them to break them, so of course it kills them. The world breaks everyone and afterward many are strong in the broken places. But those that will not break it kills. It kills the very good and the very gentle and the very brave impartially. If you are none of these you can be sure it will kill you too but there will be no special hurry. --- A Farewell to Arms, Ernest Hemingway
I'll fight them, I'll fight them until I die. --- The Old Man and the Sea, Ernest Hemingway