"I'm a rocket man, not a religious man."

"Conquering the universe one has to solve two problems: gravity and red tape. We could have mastered gravity."

"A good scientist is a man with an original mind who can think straight, but who also has a practical sense of what is possible."

"Not joining [the Nazi Party] would have meant that I would have had to abandon the work of my life."

"The Earth is too small for us."