“It was a crazy idea. But, as usual, that’s all Percy had.”

On leadership and the relation between madness, heresy, and genius.
Ideas as Art (2006)

On conversations with Rabindranath Tagore, as quoted in Uncommon Wisdom: Conversations With Remarkable People (1988) by Fritjof Capra, who states that after these "He began to see that the recognition of relativity, interconnectedness, and impermanence as fundamental aspects of physical reality, which had been so difficult for himself and his fellow physicists, was the very basis of the Indian spiritual traditions."
As quoted in Pride of India (2006) by Samskrita Bharati. p. 56
Variant: After the conversations about Indian philosophy, some of the ideas of Quantum Physics that had seemed so crazy suddenly made much more sense.

Source: Forever Peace (1997), p. 249

Source: Life is Elsewhere

"Crazy for This Democracy" in Negro Digest (December 1945).
Context: I accept this idea of democracy. I am all for trying it out. It must be a good thing if everybody praises it like that. If our government has been willing to go to war and sacrifice billions of dollars and millions of men for the idea I think that I ought to give the thing a trial.
The only thing that keeps me from pitching head long into this thing is the presence of numerous Jim Crow laws on the statute books of the nation. I am crazy about the idea of Democracy. I want to see how it feels.

Source: Ten Things We Did

"How Do People Get New Ideas?" (1959)
General sources