In this quote, on page 446 of the Book Thief, Zusak is stressing the idea that without the knowledge of words and not knowing the extreme power they contain, humans wouldn't be able to fufill their desires and express the potential they have hidden deep inside of them. Whether one uses these words to discriminate and disparage a certain race, or instead take the same words to heal, save, and to fight against justice, it all relies on the specific diction used. In many ways, the Holocaust was a war fought with words. It relied on mass communication to convey it's message of hate and to mobilize a nation in it's service. For example, Hitler did indeed understand "the true power of words," he knew exactly what to say and the appropriate time to say it. For this reason, he took advantage of the people and brainwashed them with his delicately chosen words. On the other hand, Liesel opposed the idea of using words to manipulate people, she decided that they had so much more meaning and capability. She took simple words and embraced their power to convey ideas and to kindle an inner revolution: that words are meant to inspire and not to belittle. Afterall, Liesel's love of words were so powerful they actually end up saving her life towards the end of the book since she'd rather go read and write during the bombings that destroyed Himmel Street. It's no question words had affected Hitler's followers or Liesel's family and friends. But the initial reason that makes this statement true is that words can never be taken away from one. That's what makes word's different. You can get your house taken up, your family, and even your life, but words are always left behind.