John Naisbitt (2006). Mindset. Harper Collins Publishers.

The letter Charles Darwin, the man who shook the foundation of our origins and destiny, wrote at the end of his life:

"Up to the age of 30, or beyond it, poetry gave me pleasure. But now for many years i cannot endure to read a line of poetry. my mind seems to have become a kind of machine for grinding general laws out of large collections of facts, and if I had to live my life again, I would have made a rule to read some poetry and listen to some music several times every week. The loss of these tastes is a loss of happiness, and may possibly be injurious to the intellect and more probably to the moral character, by enfeebling the emotional part of our nature."