“Men can only be happy when they do not assume that the object of life is happiness.”

“The important thing is not to stop questioning; curiosity has its own reason for existing.”

“As we advance in life it becomes more and more difficult, but in fighting the difficulties the inmost strength of the heart is developed.”

“There has to be evil so that good can prove its purity above it.”

“They can because they think they can.”

“Religion is a culture of faith; science is a culture of doubt.”