In Darwin's dangerous Idea: Evolution and the Meanings of Life, Daniel Dennett describes Darwin's idea as the "best idea anyone has ever had."

In a single stroke, the idea of evolution by natural selection unifies the realm of life, meaning, and purpose with the realm of space and time, cause and effect, mechanism and a physical law. But it is not just a wonderful scientific idea. It is a dangerous idea.

What exactly was Darwin's dangerous idea? According to Dennett, it was "not the idea of evolution, but the idea of evolution by natural selection, an idea he himself could never formulate with sufficient rigor and detail to prove, though he presented a brilliant case for it." (42) Dennett considers Darwin's idea to be "dangerous" because it has so many fruitful applications in so many fields above and beyond biology. When Dennett was a schoolboy, he and some of his friends imagined that there was such a thing as "universal acid,"

a liquid "so corrosive that it will eat through anything! The problem is: what do you keep it in? It dissolves glass bottles and stainless steel canisters as readily as paper bags. What would happen if you somehow came upon or created a dollop of universal acid? With the whole planet eventually be destroyed? What would it leave in its wake? After everything had been transformed by its encounter with universal acid, what would the world look like? Little did I realize that in a few years I would encounter an idea-Darwin's idea-bearing an unmistakable likeness to universal acid: eats through just about every traditional concept, and leaves in its wake a revolutionized world-view, with most of the old landmarks are still recognizable, but transformed in fundamental ways.

(63) Darwin's idea is powerful, indeed. Many people see it as having the power to ruin the meaning of life.

People fear that once this universal acid has passed through the monuments we cherish, they will cease to exist, dissolved in an unrecognizable and unlovable puddle of scientific destruction.

Dennett characterizes this fear is unwarranted:

We might learn some surprising or even shocking things about these treasures, but unless our valuing these things was based all long on confusion or mistaken identity, how could increase understanding of them diminish their value in our eyes? (82)