"First principle: never to let one's self be beaten down by persons or by events."

"I had to work for my living, and I had to study. It was a very hard time for me."

"My husband and I were so closely united by our affection and our common work that we passed almost our whole time together."

"After all, science is essentially an international thing."

"A scientist must be a child. He must be curious. He must be eager to learn. He must be willing to make mistakes."