Human spirit is the ability to face the uncertainty of the future with curiosity and optimism. It is the belief that problems can be solved, differences resolved. It is a type of confidence. And it is fragile. It can be blackened by fear and superstition.
I respond well to what I read of Immanuel Kant's idea that the world as we see it is absolutely a function of the way our brain works. In the modern parlance, it's an evolved machine that we carry with us.
Thought, like any parasite, cannot exist without a compliant host.
Superstition is the need to view the world in terms of simple cause and effect.
The successful Idea travels from mind to mind, claiming new territory, mutating as it goes.
I didn't study science beyond high school level, but I'd been reading a lot of science books by people like Richard Dawkins, Matt Ridley and Daniel Dennett. I also spent a year working on a fellowship in a research centre - the Allan Wilson Centre - where I got a hands-on look at their work sequencing DNA.