"I have been interested in phenomena involving complexity, diversity and evolution since I was a young boy"

"The young man knows the rules, but the old man knows the exceptions"

"Neurotics complain of their illness, but they make the most of it, and when it comes to talking it away from them they will defend it like a lioness her young"

"Young men have a passion for regarding their elders as senile"

"Youth is not a question of years: one is young or old from birth"

"No worse fate can befall a young man or woman than becoming prematurely entrenched in prudence and negation"

"In America the young are always ready to give to those who are older than themselves the full benefits of their inexperience"

"I shall not die young, for I am already near seventy: I may die old"

"There are few things more dishonorable than misleading the young"

"The first symptom of love in a young man is timidity; in a girl boldness"

"Anyone who stops learning is old, whether at twenty or eighty. Anyone who keeps learning stays young. The greatest thing in life is to keep your mind young"